My teacher named the assignment "Factor with X." This is the equation I am having trouble with:
7b^2-71b+10

Question

My teacher named the assignment "Factor with X." This is the equation I am having trouble with:
7b^2-71b+10

anonymous · Answer

a*b=70
a+b=-71

anonymous · Answer

what are the factors of 70

anonymous · Answer

1*70
2*35
etc..

anonymous · Answer

now which pair of factors could "add" up to -71

anonymous · Answer

:)

anonymous · Answer

I understand that, but it's really hard for me to figure out those factors....

anonymous · Answer

Oh yeah, I forgot to thank you.

mathmale · Answer

"7b^2-71b+10" has the same form as does 7x^2-71x+10, and thus its factors are quite similar to those of 7x^2-71x+10.

Note how Ludwig took the first and last coefficients of 7b^2-71b+10 (7 and 10) and multiplied them together to obtain 70.  He then asked you to list possible factors of 70.  Lastly, you need to identify which set of factors combines to result in the coefficient -71 of the middle term.

anonymous · Answer

I think I realize now that I know what to do, but I just can't seem to find the numbers.
Thank you.