+0

# It seemed like this question got skipped over and I really need help with it.

0
89
15

Mar 21, 2020

#1
+3

This is what I got--

(6x^3*4)+(4x^2*3x)+(-7x*3x^2)+(-5*6x^3)
24+12-21-30 = -15

Therefore, the coefficient would be -15.

Hope this helped!

Mar 21, 2020
#2
0

Thanks for the help!!!

qwertyzz  Mar 21, 2020
#3
+1

Of course :D

CalTheGreat  Mar 21, 2020
#4
0

The two expressions are to be MULTIPLIED by each other, not ADDED, which is what you got !!!

Guest Mar 21, 2020
#14
0

qwertyzz  Mar 21, 2020
#5
+1

Qwerty would you like me to answer on the original question? I guess I could

Mar 21, 2020
#6
+1

I can try again.... It's just factoring.

Mar 21, 2020
#7
+1

I posted an answer on the original question. If you'd like, you can check my answer

jfan17  Mar 21, 2020
#8
0

Expand the following:
(24 x^4 + 6 x^3 + 4 x^2 - 7 x - 5) * (6 x^3 + 3 x^2 + 3 x + 4)

=144 x^7 + 108 x^6 + 114 x^5 + 84 x^4 - 15 x^3 - 20 x^2 - 43 x - 20

Mar 21, 2020
#9
+1

Hey guest! Could you explain how you got to that answer?

jfan17  Mar 21, 2020
#10
+1

I just checked with an online polynomial expander, and it appears my answer of -15 was correct. How exactly did you arrive at your answer of -43?

EDIT: I think you arrived at the right polynomial. It's just asking for the x^3 term, not the x term :P

jfan17  Mar 21, 2020
edited by jfan17  Mar 21, 2020
#11
0

Yes! I got Mathematica 11 Home Edition on my computer.

Guest Mar 21, 2020
#12
0

Sorry! I highlighted the x term instead of x^3, which is -15 as you can see.

Guest Mar 21, 2020
#13
+2

Mar 21, 2020
#15
+1

What is the coefficient of x^3 when 24x^4 + 6x^3 + 4x^2-7x - 5 is multiplied by 6x^3 + 3x^2 + 3x + 4 and the like terms are combined?

( 24x^4 + 6x^3 + 4x^2 - 7x  - 5)  *  ( 6x^3 + 3x^2 + 3x + 4)

The coefficient  on  x^3  will be found  as

6x^3 * 4   +  4x^2 * 3x  - 7x* 3x^2  -5*6x^3  =

[ 6* 4  + 4*3   - 7*3  - 5*6 ] x^3   =

[24  + 12  - 21   - 30  ] x^3  =

-15 x^3   Mar 21, 2020