did I do this problem right?Explain, in complete sentences, how you would completely factor 15x2 – 25x – 60 by using the grouping method. How would you check your factors for accuracy?

Question

anonymous · Answer

First you would divide  by 5:
5 (3x^3 - 5x - 12)

now you need to find two numbers whose product is -12 and where the result of multiplying  by 3 and adding give the middle number -5


- 3 * 4 = -12
and -3*3 + 4 = -5

so you then put them in parenthesis to get:
(3x + 4)(x - 3)   ( + 4x  - 9x = -5x)

then you get:

5(3x + 4)(x - 3)

would this be right?

anonymous · Answer

no you are bot doing it right, you have to find two numbers whose product is =-12*3=-36 and not -12, so the numbers would be -9 and 4...now proceed using these valued to get a right answer

anonymous · Answer

3x²-9x+4x-12


(3x²-9x)+(4x-12)
3x(x-3)+4(x-3)

x-3 is a common factor.so isolate that would be:
(x-3)(3x+4) 

Solving:
x = 3 or x = -4/3
{3, -4/3}

would this be right ?

anonymous · Answer

yes u got it now

anonymous · Answer

ok thanks!!!