Answer:
![5x^4 + 15x^3 - 4x^2 + 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fk2a0tpwp8vzp4c7alyp81ah3rpi26uww9.png)
Explanation:
![(7x^3 + 5x^4 + 3x^2) - (7x^2 - 7 -8x^3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/96vz0oody4xe71bjknno45go85o8i26he4.png)
what we need to do is distribute the - sign in the middle of the parentheses into (7x^2 - 7 -8x^3)[/tex], this is very important to ensure we have the correct answer. by distributing we get the following equation:
![7x^3 + 5x^4 + 3x^2 - 7x^2 + 7 + 8x^3](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1qyq54konxq60gi2bxpg76vnt7m6jsyuer.png)
now we combine like terms to get our answer
stays as it is, since there is nothing to combine it with
7x³ + 8x³ = 15x³
3x² - 7x² = -4x²
7 stays the same because like
, there is nothing else to combine it with
we have the following new equation:
![5x^4 + 15x^3 - 4x^2 + 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fk2a0tpwp8vzp4c7alyp81ah3rpi26uww9.png)