







An impossible problem 
20170915 

From Fay: Given math homework problem of: Gary and Larry given 2 numbers and told to add together. Gary subtracted and got 14. Larry multiplied and got 799. I tried substitution:
XY=14 and X x Y=799
X= Y+14
(Y+14) Y=799 and here I'm stuck at Y squared+14 Y= 799
using substitution I got 47x17=799 but not 14b when subtracted. HELP????? Answered by Penny Nom. 





Linear equations in two variables 
20151213 

From priya: I have problem in solving these equations please help me today itself very urgent:
I)2x+y=y
II)pie*x+y=9 Answered by Penny Nom. 





Differentiate x^x  2^sinx 
20130809 

From tarun: derivative of x^x  2^sinx Answered by Penny Nom. 





An equation in two variables 
20130514 

From Steve: Verify solutions to an equation in two variables. 4x2y=8 (3, 2) Answered by Penny Nom. 





Introductory algebra 
20121030 

From kevon: if x = 7 is used in the expression 2x + 5 what is the output Answered by Penny Nom. 





Minutes and seconds 
20120829 

From Casey: I have to write a variable equation. The questions says there are 60 seconds. but we need to write and equation to solve for minutes. Is it 1/60 or 1/s Answered by Robert Dawson. 





Coefficient of variation 
20110414 

From Braden: When determining coefficient of variation (CV) or %CV is it possible to calculate %CV for two variables? For instance can %CV be used to determine the precision of 5 data points on a graph using the X and Y coordinates? or does %CV need to be determined for each variable separately? Answered by Robert Dawson. 





A binomial random variable 
20101129 

From yvette: a binomial random variable has a mean equal to 200 and standard deviation of 10. find the values of n and p. Answered by Penny Nom. 





Simultaneous Equations 
20090706 

From Mukulu: Solve the equation simultaneously X/5=(Y+2)/2= (Z1)/4 ……………….eqt 1
3X+4Y+2Z25=0 ………………eqt 2 Answered by Janice Cotcher. 





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. 





6^x = y 
20090212 

From Jamie: Find x:
6^x=y Answered by Harley Weston. 





The whole number that precedes a number w+3 
20090117 

From Morgan: write a variable expression for
"The whole number that precedes a number w+3" Answered by Penny Nom. 





An expression for q quarters and n nickles 
20090116 

From Morgan: a variable expression for:
"The value in cents of q quarters and n nickels" Answered by Penny Nom. 





Equations with the variable in the exponent 
20081028 

From fari: Solve for x
5 * 4^x3=40
5^x=25^(x+8) Answered by Penny Nom. 





A homework problem 
20081028 

From Shawn: I'm checking my son's homework and we disagree on the solution.
The problem reads:
135mn^4 (n to the 4th power) over 50n^2 (n squared)
I think the answer is: 27mn^2 (squared) over 10
Can you help? Answered by Penny Nom. 





An algebraic expression 
20080829 

From Antonio: write a variable expression for 9 less than k Answered by Penny Nom. 





Solve for y in terms of x 
20080810 

From Rosie: Solve equation for y
4x=12+3y Answered by Penny Nom. 





Solving for Two Variables 
20080724 

From Mary: can you help,
2/35= 1/x +1/y ; x Answered by Janice Cotcher, Victoria West and Harley Weston. 





g(m1,2n)+n 
20080607 

From Florence: What does g(m1,2n)+n for m>0, n>=0 mean. Answered by Penny Nom. 





How do you reduce an equation with multiple variables? 
20080430 

From Jonathon: How do you reduce an equation with multiple variables?
For example, if 3x + y = k(x3), what would x be equal to? Answered by Penny Nom. 





A dependent variable 
20080130 

From lavada: i need the definition to dependent variable Answered by Stephen La Rocque. 





Working with x 
20071012 

From Robert: The question: The measure of an exterior angle of a regular polygon is given. Find the measure of an interior angle, and find the sides.
41. 36 42. 18 44. 'X'
The attachment has what she has done for 41 and 42. Need help with 44 (lots of help) Thank you in advance for your site and your help. Robert Answered by Penny Nom. 





Express a certain variable as a function of another variable 
20070612 

From Gilligan: The volume V of a right circular cone is V = (1/3)pi(r^2)(h). If the height is TWICE the radius, express the volume V as a function of r.
I see the phrase "express a certain variable as a function of another variable" a lot in math books.
What exactly does that mean?
Is there another way to say the same thing? Answered by Stephen La Rocque. 





Three equations in three unknowns 
20070318 

From Shawna: You are told that you are working with three different numbers. When the first number is added to twice the other two numbers, the result s 64( i.e x+2y+2z= 64). When the second number is added to twice the other two numbers the result is 62 (y+2x+2z=6). Finally, when the third number is added to twice the other two numbers, the resut is 59 z+2x+2y=59) Determine the three numbers? Answered by Penny Nom. 





How do you write a variable expression 
20061011 

From Josh: How do you write a variable expression for the following:
The amount of money Waldo has if he has $10 more than Joe and
How much weight Kirk can lift if he lifts 30 lbs more than his brother. Answered by Stephen La Rocque. 





Parameters 
20060915 

From Chase: What is the meaning of the word "parameters" when used in reference to Algebra. Answered by Penny Nom. 





Degree 
20060209 

From Jessica: I am a 9th grade home school student and have started doing degrees of terms in my math book. The following is some examples they give:
25a to the 4th power is a 4th degree term
67c to the 9th power is a 9th degree term
x is really x to the 1st power so it is a 1st degree term
10 is really 10x to the 0 power so it is a 0 degree term
They go on to say that every constant is a zero degree term.
My question is why isn't a constant, like 10, simply to the 1st power (making is a 1st degree term) like x. Answered by Claude Tardif. 





Simplify the variable expression: 3g^2h over 12gh 
20060209 

From Andrew: okay the question says simplify the variable expression: 3g^{2}h over 12gh
how would u do this? Answered by Penny Nom. 





I = PRT 
20051116 

From Ryan: Use the formula to find the value of the variable that is not given:
I=PRT;I=$2880, R=0.08, P=$12,000 Answered by Penny Nom. 





A variable rectangle 
20051108 

From Mussawar: find the lengths of the sides of a variable rectangle having area 36 cm^{2} when its perimeter is minimum i do not want solution of this question. i would like to know what is mean by variable rectangle.and what is difference between rectangle and variable rectangle.also what is mean by when its perimeter is minimum. Answered by Penny Nom. 





Can we take the derivative of independent variable 
20051018 

From Mussawar: why we take derivative of dependent variable with respect to independent variable .can we take the derivative of independent with respect to dependent.if not why. Answered by Walter Whiteley. 





Coefficients, constants and like terms 
20051005 

From Elizabeth: In the equation 8y+6ab+73ab what are the coefficients; the like terms and constants? Answered by Penny. 





Solve for a and t 
20041023 

From Justin: How do I solve for "a" and "t" in the equations:
1000t= 4000 + 2000t + (1/2)at^2
1000=2000 + at Answered by Penny Nom. 





x^2/3  7 x^1/3 + 12 = 0 
20040405 

From Jackie: I am having trouble solving this question for x:
1.) x^2/3  7 x^1/3 + 12 = 0 Answered by Penny Nom. 





The quadratic formula 
20030831 

From Alex: I am using Houghton Mifflin's Precalculus with Limits book, 2nd edition. However, the first chapter encompasses Algebra review, and I am stuck on a problem. All that's required is to solve the following and verify using a calculator: 3y2+6y+2=0 I have solved the problem using the quadratic formula, but from what I remember, the quadratic formula is used in the case of equations following the AX2+BX+C=0 pattern. As the problem I am attempting uses a yvariable, can I still use the quadratic formula? Since I am not sure what route to take in solving this problem, I am hoping you can assist me. Answered by Harley Weston. 





A rule with a variable 
20030824 

From Crystal: what is a rule with a variable Answered by Penny Nom. 





Water in a cone 
20030812 

From Adrienne:
Water is poured into a tank in the shape of an inverted right circular cone.ð The height of the tank is 8 m and its radius at the top is 4 m. a. Draw and label a picture to represent this situation.ð (I know how to do this) b. Identify all variable quantities. (h = 8m, r = 4m) c. Find an equation that relates the variable quantities, and reduce the number of variable quantities to two. I was thinking about the equation V = 1/3 pi r^{2} h, which is the Volume of a cone, but I am stumped as to how I am supposed to "reduce the number of variable quantities to two." Can you point me in the right direction? Answered by Penny Nom. 





x6square root of x +8=0 
20030510 

From Elizabeth: x6square root of x +8=0 Answered by Penny Nom. 





Simplifying Variable Expressions 
20021028 

From Erika: i would like to ask you a mathematical question on Simplifying Variable Expressions. The question is 2(n4)+3. Answered by Penny Nom. 





Variable expressions 
20020815 

From Brittany: I am just learning variable expressions. My homework is to write a variable expression for each word phrase;
example :
the number of minutes in s seconds the cost of x cartons of juice at $.75 each And etc.
I don't understand it Answered by Penny Nom. 





3 = 2x 
20020505 

From Timothy: My question is 3 = 2x How do I isolate the variable here? Answered by Penny Nom. 





Factor completely 
20020307 

From Taylor: I'm supposed to completely factor this but I don't know what to do with all the variables. a^{3}b^{5}  a^{2}b^{5}  12ab^{5}. Does it have anything to do with b^{5} being a common factor or am I completely off? Answered by Penny Nom. 





Solve for the variable 
20010228 

From Ashley: I've got 2 questions. We (my dad and I) can not figure them out. please help me.  21 = 9  2 (4a + 2) and I am supposed to find out what the variable is.
 2/3 n + 3/8 n = 15/16 (those are fractions). Again, I need to find out what the variable is.
Answered by Penny Nom. 





Solve for two variables 
20010225 

From A student: How do I solve for %1 and %2 in the following formula when T1, T2 and T3 are known? %1 and %2 are ratios of the same element, therefore %1 + %2 = 100%
(%1 x T1) + (%2 x T2) = T3 Answered by Penny Nom. 





Some complex problems 
20010115 

From Nick: I am having enormous difficulty with one question in my maths homework. The question is shown below. If anybody out there can find the answers and show the workings and help me to understand. Answered by Harley Weston. 





Random 
19980915 

From Hugh Ballantyne: I am an occasional teacher. Here is my question: Does the word "random" have a technical meaning in mathematics? Answered by Harley Weston. 





The Central Limit Theorem 
19970421 

From Donna Hall: A skeptic gives the following argument to show that there must be a flaw in the central limit theorem: We know that the sum of independent Poisson random variables follows a Poisson distribution with aparameter that is the sum of the parameters of the summands. In particular, if n independentPoisson random variables, each with parameter 1/n, are summed, the sum has a Poisson distributionwith parameter 1. The central limit theoren says the sum tends to a normal distribution, butPoisson distribution with parameter 1 is not normal. What do you think of this argument? Answered by Neal Madras. 

