Question

Subtract -2k3 + k2 - 9 from 5k3 - 3k + 7.

Answer 1

5k3-3k+7-(-2k3+k2-9)
basically rewrite with simple algebra principles
15k-3k+7-(-6k+2k-9)
split up the parenthesis
15k-3k+7+6k-2k+9
sort them
15k-3k+6k-3k+7+9
short down by adding up the similar factors
answer: 18k+18
factorise
18(k+1)
both forms are right

Answer 2

Answer:  The required value is $7k^3-k^2-3k+16.$

Step-by-step explanation:  We are given to subtract the polynomial $-2k^3+k^2-9$ from $5k^3-3k+7.$

That is, we need to find the value of S, where

$S=(5k^3-3k+7)-(-2k^3+k^2-9)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)$

To perform the given subtraction, we need to combine the like terms as follows :

$S\\\\=(5k^3-3k+7)-(-2k^3+k^2-9)\\\\=5k^3-3k+7+2k^3-k^2+9\\\\=(5+2)k^3-k^2-3k+(9+7)\\\\=7k^3-k^2-3k+16.$

Thus, the required value is $7k^3-k^2-3k+16.$