







Slicing an inverted bowl at various heights 
20170430 

From Joel: Find a formula to calculate the circumferences of an inverted bowl at various heights.
E.g. Take an inverted bowl with a diameter of "x" cm and a depth / height of "y" cm.
How can I calculate the circumferences at distances of various heights above the base?
Alternately, what would be the formula to calculate the distance of the line segment resulting from a line which intersects both sides of a parabola in which that line is drawn parallel to the tangent of the vertex of the parabola at any given distance from the vertex? Answered by Penny Nom. 





The inverse of y = x(x  2) 
20161221 

From Sasha: Hello, I recently stumbled upon this question and I haven't been able to figure it out.
Why is the inverse of y=x(x2) not a function?
Suggest a domain restriction which would ensure that the inverse is a function.
Thank You :) Answered by Penny Nom. 





Inverting fractions and percentage 
20130518 

From Carlos: If I calculate the percentage change between two fractions, say,
1/100 and 2/100, I get 100% change. Now, if I flip denominator
and numerator, 100/1 and 100/2, and repeat the calculation, I
get a 50% change. Why are the percentages different?
Thank you very much Answered by Penny Nom. 





Proof of a Unique Solution 
20090724 

From muele: Find matrix A such that A is not invertible, and
b such that Ax=b has a unique solution Answered by Robert J. Dawson. 





Student who is inverting digits 
20081209 

From Tammie: Do you have any strategies for addressing inversion of digits in two digit numbers. For example  The student the teacher is working with will write "14" and the number is 41. She has tried highlighting, practice writing numbers, and hundreds charts and finding patterns. Help! Thank you! Answered by Robert Dawson and Victoria West. 





y = log(x) + x. Solve for x. 
20050826 

From Alain:
I have the following equation:
y = ln(x) + x
How do I solve for x?
Answered by Penny Nom. 





The inverse of a quintic function 
20040722 

From A student: I'm really having trouble finding out the inverse of this quintic equation. F(X)= X^{5}+3X^{3}+1.I know that this quintic has an inverse because it is one to one. But I can't find a method to solve this. Finding the inverse of a quadratic or a cubic equation is a lot easier, but with this quintc I am really lost. I even know how the graph of this equation and its inverse looks like, but I'm not sure if Iam getting the right equation. Please help me out. Answered by Penny Nom. 





If the matrix A is inverible and AB =AC, then B = C 
20020327 

From Vikki: i hope you can help i am soooo stuck here goes: a)
A= 0 1 B= 1 1 c= 2 5 0 2 3 4 3 4
A,B and c are matrices Evaluate AB and Ac (which I can do) then
b) I need to prove that if the matrix A is inverible and AB =AC, then B = C. Why does this not contradict what happened in part a)? Answered by Leeanne Boehm. 





Inverting a function 
20010930 

From Brandie: Could you please tell me what is the basic guideline for inverting a function Example: S(R)=2PiRal V(R)=PiR(squared)bl R(V)=? Answered by Claude Tardif. 





Dividing fractions 
20001018 

From Paula: Why do you have to change the division sign to a multiplication sign and invert the fraction that follows the division sign in order to get the answer to a division problem when you're working with fractions? Answered by Penny Nom. 





Graphing cube roots 
20000427 

From Heather Jones: What do the graphs of cube roots look like? Answered by Walter Whiteley. 





Domain and Range of a Function 
19991114 

From Michelle Mellott: How do you find the range of the following function: 2y^{2}/(y^{2}+5y+6)?? I know the domain is x not equalled to 2, 3. How can one easily find the range? Answered by Harley Weston. 





Invert and multiply 
19990828 

From Debbie Walter: I have another question please, WHY do we invert and multiply when dividing fractions? I know that's what we do but WHY? What is the reasoning behind it? Answered by Penny Nom. 

