







A sulphuric acid solution 
20180712 

From Tan: How much 96% h2so4 to add into sulphuric acid 30% in order to make it to 50% sulphuric acid? Answered by Penny Nom. 





Extraneous solutions 
20150307 

From Emily: I have a question about Extraneous Solutions, Because I was recently researching to figure out
on how to determine that a solution is extraneous and many of the answers talked about how if a answer is negative
that it should always be extraneous but now I found out that positive solutions can also be considered as extraneous solutions
so that is why I am really confused Extraneous Solution's.
I would really appreciate it if you could clearly explain to me how to determine an extraneous solution from a normal solution.
Thanks,
Emily Answered by Chris Fisher. 





One zero to a quadratic expression 
20141006 

From Kevin: Find a value of n such that f(x) = 3^x2 + nx + 6 only has one zero, is this the only solution to the question? Answered by Penny Nom. 





A 7% solution 
20140114 

From imran: what amount of H2SO4 should be added to make 5mL of 0.7% H2SO4 solution Answered by Penny Nom. 





Extraneous solutions 
20131022 

From tom: i need an equation where x=2 is the correct answer and x=3 is an extraneous solution. can you provide me with such an equation?? Answered by Harley Weston. 





Dilution of concentrated acid 
20130731 

From Adom: I have 500mls of 90% conc. of an acid. Now I need to prepare 20% concentration from this (say 100mls of this). How much of the stock solution do I take and how much water to add? Thanks! Answered by Penny Nom. 





Extraneous solutions 
20130218 

From Eileen: (5x+4)^1/23x=0 Answered by Penny Nom. 





A 25% sulfuric acid solution 
20120503 

From Scott: In order to make a 25% solution with 96% Sulfuric Acid, how much of the Sulfuric do I add to DI water to make up 2000ml?? Answered by Penny Nom. 





Extraneous solutions 
20100522 

From Joe:
Question from Joe, a parent:
w+3 2w
   = 1
w21 w1
W2 is = w squared
4
The answer is w= 
3
but have no idea how this was solved. any help is appreciated. Thanks. Answered by Penny Nom. 





A rectangle problem 
20100412 

From Charlene: The ratio of the width to the length of a certain rectangle is equal to the ratio of its length to the difference between its length and twice its width. If the area of the rectangle is 25cm^2, then what are its dimensions? Present a non algebraic solution? Answered by Tyler Wood. 





Redwood Park and Glendale Park 
20100305 

From Shaun: Question from Shaun, a student:
Redwood and Glendale Parks are each surrounded by 100 yards of
fencing. The are of Redwood Park is 25 square yards more than the area
of Glendale Park. If both parks are rectangles, what is the measurement
of each rectangle? Answered by Harley Weston. 





Find the intersection of y=x1 and y=sin(x) 
20091010 

From Usama: There are many modern calculators and softwares that can plot the functions.
I have two very simple equations y=x1 and y=sin(x), if i draw them manually on paper i can not get the accurate value.
But i think a computer can easily draw perfect straight and curve lines so it should be easy to find the intersection point of two lines.
Is there any way or software that can tell the exact value of intersection point of two lines? Answered by Robert Dawson and Harley Weston. 





A solution of 45% acetic acid 
20090928 

From Autumn: if a chemist has a 4 liter solution that consists of 90% acetic acid, how much water does he need to produce a solution of 45% acetic acid? Answered by Penny Nom. 





Extraneous solutions 
20090920 

From iyana: what is an extraneous solution? what must you do to determine whether a extraneous solution? Answered by Stephen La Rocque and Harley Weston. 





Percentage of Acid 
20090717 

From Leeanne: here is my question:
a chemist has 200 liters of solution that is 5% acid. how many liters of water
(0% acid) must he add to make a solution that is 4% acid? Answered by Stephen La Rocque. 





Extraneous solutions 
20090602 

From Ayana: solve and check for extraneous solutions.
3x+6/ x²4 = x+1/ x2
x can not = {2,2} Answered by Penny Nom. 





An infinite number of solutions 
20090324 

From Sean: this is a linear equations problem;
first:
3535.5 + Fbd (.866) + Fbc (.5)  Fab (.5) = 0
and
3535.5  Fab (.866)  Fbc (.5)  Fbd (.5) = 0 Answered by Harley Weston. 





Linear systems 
20090220 

From Rose: I have been having trouble trying to figure out these three math problems , I need help breaking them down so I could understand them better please help.
1. x = 7  x
2 x  y + 8
2. 8 x + 5 y = 1 8 4
x  y = 3
3. y + 2 x = 3
y + 2 x = 4
I can't figure out how to break them down in the right order. Answered by Penny Nom. 





A 10% salt solution 
20090112 

From Joanna: How many liters of water must evaporate from 40 liters of a 10% salt solution to make a 25% salt solution? Answered by Robert Dawson and Penny Nom. 





A quadratic 
20081027 

From Giselle: 3x squared minus 2x equals 5 Answered by Penny Nom. 





The ratio of two chemicals 
20081020 

From Nathan: if there is a chemical mixture of 5:2 and the total amount of the entire solution is 1400 gallons, how many gallons make up the stronger side of the solution? I believe the answer is 1,000 but I figured it out in a nontraditional way so I wanted to understand the basic formula used to determine these types of questions.
thank you Answered by Penny Nom. 





A different approach to a word problem 
20081003 

From Kenneth: Sarah's age is 2/3 of Mary's age and 3/4 of Ruth's age. The sum of their ages is 46 years. How old is each? Answered by Penny Nom. 





Extraneous solutions 
20080925 

From crystal: /6x+7/=5x+2 Answered by Penny Nom. 





algebra 
20080731 

From Eric: Would you please solve & explain this equation to me: x^2+2x=x(x+2)?
Thank you Answered by Penny Nom & Stephen La Rocque. 





A inear system 
20080203 

From Kelly: is (1,5) a solution of each system? y=x+4 y=1/5x Answered by Penny Nom. 





A linear system 
20080122 

From Lisa: I am supposed to use augmented matrices to solve this system of equations. x  3y = 5; 4x  12y = 13. I think it is unsolvable but I want to be sure I am not just giving up. Thanks in advance for your help! Lisa. Answered by Stephen La Rocque and Brennan Yaremko. 





Number of real solutions 
20071005 

From Sujith: The no of real solutions of the equations 1+x+x^2+x^3 = x^4+x^5 is ? Answered by Harley Weston. 





Two equations in two unknowns 
20070922 

From Mary: Having problems doing this problem, looking for a solution with the work. I would like to see how you got your answer, to see what I was doing wrong.
solve using the substitution method, is there "no solution" or "infinitely many solutions"
4x+y=4
2x+8y=0 Answered by Stephen La Rocque and Leeanne Boehm. 





What feature on a graph shows the solution? 
20070819 

From San: To solve the equation 2sinx+square root 3=0, what feature of the graph,
in the form y=asinx+b would show the solution? Draw a graph to show
the solution. thanks. Answered by Stephen La Rocque. 





What happens when you have zero's on both sides? 
20070605 

From Lily: On the substitution method what happens when you have zero's on both
sides of the equation? Is that considered no solution or infinitely many? Answered by Stephen La Rocque and Penny Nom. 





No solution to a linear system 
20070409 

From Ryan: When is it possible to get no solution when solving a linear system? Answered by Leeanne Boehm, Steve La Rocque, Penny Nom and Melanie Tyrer. 





How many milliliters of solution should be administered 
20060822 

From Traci: If a solution contains 4 percent , how many milliliters of solution should be administered to give a patent 80 grams? Answered by Stephen La Rocque. 





Diluting an acid solution 
20060225 

From Alex: IF YOU HAVE 1 Litre OF A 70% ACID SOLUTION, AT WHAT RATIO DO YOU DILUTE IT WITH WATER TO ACHIEVE A 30% AND 50% ACID SOLUTION? Answered by Penny Nom. 





Extraneous solutions 
20060101 

From Liz:
Question: solve and check for extraneous solution
3(w + 1)^{1/2} = 6
Answered by Penny Nom. 





How many pixels are there to an inch? 
20051015 

From Fred: I want to know how many pixels there are to an inch. Answered by Penny. 





Extraneous solutions 
20050204 

From Heather: My teacher wants to know why there are extraneous solutions in logarithms? Answered by Penny Nom. 





Extraneous solutions 
20040728 

From Nicole: When I have a problem like (2x + 3)/5 = (x + 1)/6 and the question asks to check for extraneous solutions, how do you solve that? Answered by Penny Nom. 





Preparing 100ml of a 30% alcohol solution 
20030713 

From Justin: My question is how do you prepare a 100ml of a 30% alcohol solution using 95% alcohol? Answered by Penny Nom. 





Extraneous solutions 
20030124 

From Paul:
What is an extraneous solution and in what cases do you get one? How do you know it is extraneous? Answered by Penny Nom. 





Mixing solutions 
20020913 

From Margaret: In a chemistry laboratory the concentration of one solution is 10% hydrocholoric acid (HCl) and that of a second soulution is 60% HCl. How many mL of each should be mixed to obtain 50 mL of a 30% HCl solution?? Answered by Penny Nom. 





A solution to an equation 
20020828 

From A student: How do you determine whether a pair of numbers is a solution for an equation? If you could identify the specifics steps I need to take to determine whether it is a solution or not would be appreciated! Thanks i.e. x4=0 Pairs of numbers as possible solutions (4,7) (3,4) (0,4). Answered by Penny Nom. 





Common solution 
20010602 

From Samantha:
 Solve for common solution: x+y=6 2x3y=2
 Solve for y in terms of x: 3xy=4
Answered by Penny Nom. 





The solutions of a quadratic 
20010130 

From A student:
 Show that the product of the solutions of ax^{2} + bx + c = 0 is c/a.
 For each equation under the given condition, (a) find k and
(b) find the other solution. kx^{2}  2x + k = 0; one solution is 3 Answered by Penny Nom. 





Integral solutions 
20001120 

From David: determine all pairs of integers (x,y) which satisfy the equation 6x^{2}  3xy  13x + 5y = 11 I got y= (6x^{2}13x+11)/(3x5) and i don't konw how to continue Answered by Claude Tardif. 





sin x = x/10 
19991007 

From Amandeep Grover: Solve the equation sin x = x/10 Answered by Harley Weston. 





Algebra 
19981125 

From Casey: yeah my son brought home a math worksheet and he was wondering and me too if u could help him and me out . he has problems like this 4n+9=7n+2= ??? and he has to show work so if u could help us out that would be great Answered by Jack LeSage. 





A Linear System 
19981008 

From Jason Bussey: The linear systems with the following pattern all have the same solution. Is their some kind of reasoning as to why this is so? 2x+3y=4 3x+4y=5 4x+5y=6 5x+6y=7 The solution is always x=1, y=2 Thank you Jason Answered by Penny Nom. 





Graph question 
19980512 

From Rose Seminary: Why is the point of intersection of two lines the solution to the corresponding system of equations? Answered by Penny Nom. 





Approximating roots. 
19961104 

From Ben Dixon: How do you calculate a square root? eg the square root of 2.There is obviously some sort of successive approximation type algorithm for doing it to however many decimal places is required, but what is the algorithm? Answered by Harley Weston. 





Résolution d'une équation 
20100225 

From sellin: Il faut que j'exprime x en fonction de m dans l'équation suivante et je n'y arrive pas:
3x + 1 = (m1) / 2 * x + (2m + 3) / 5 Answered by Claude Tardif. 





Resolution of the equation f(x)=0 
20000401 

From Naoufal: How can i evalf the equation f(x)=0 with f function . Can you ansear me in french thank you very much Answered by Claude Tardif. 

