posted by sam on .
Megan factored the expression (-12x^2+52x-35) as (-2x+5)(6x-7) but when Jacob applied FOIL principle and multiplied out (2x+5)(6x-7) he got (-12x^2+44x-35),thus megan's solution does not appear to check please help megan to understand better.Explain your reasoning and correctly factor the original expression if possible If the expression is a prime please state so
First of all I changed it into
- (12x^2 - 52x + 35)
After 4 tries I had
- (2x-7)(6x-5) or (7-2x)(6x-5) or (2x-7)(5-6x)
(I use a method where I list the factors of the first and last numbers, and then take sum or differences of cross-products
3 2 1 ....... 5 7
4 6 12 ...... 7 5
2x5 + 6x7 = 52, my middle term
This is the fastest way to factor trinomials, too bad nobody seems to teach this method any more.
I came up with -(6x-5)(2x-7)
that was my first answer I gave you.
surely you realize that
-(6x-5)(2x-7) = - (2x-7)(6x-5)