(2x-1)(3x-7)(4x+3)

Question

=6x^2-14x-33x+7
=(6x^2-19x+7)(4x+3)
=24x^3+18x^2-126x+28x+21
=24x^3+18x^2-88x+21 <-- my answer

but the correct answer is 24x^3-50x^2-23x+21
please correct me? thank you!

Answer 1

(2x-1)(3x-7) = 6x^2-17x+7

go to calc101.com and click on the long division button.

Enter 6x^2-17x+7 and 4x+3 as your polynomials, and watch the fun! I'm sure you will find where you went wrong.

Answer 2

Sorry, make that the long multiplication button.

Answer 3

(3x-7)(4x+3) = 12 x^2 -19 x - 21
now use distributive property

2x (12 x^2 -19 x - 21)
-1 (12 x^2 -19 x - 21)

= 24 x^3 - 38 x^2 - 42 x
_________- 12 x^2 + 19 x + 21
===============================
= 24 x^3 - 50 x^2 - 23 x + 21

Answer 4

here is the link Steve is sending you to (I went and looked(
http://calc101.com/webMathematica/long-multiply.jsp

Answer 5

amazing - it got the same thing I did :)