FInd the error in the solution and then solve correctly:

Question

(X³-8x+2)+(3x³+7x+6)

X³-8x+2+3x³+7x+6

(X³+3x³)-(8x+7x)+(2+6)

4x³-15x+8

Answer 1

(X³-8x+2)+(3x³+7x+6)

X³-8x+2+3x³+7x+6

(X³+3x³)+(-8x+7x)+(2+6)

4x³-x+8

Answer 2

The negative got distributed on the x terms and made 7x into -7x which is not correct. It is supposed to be -8x + 7x which is -x, not -15x. The correct answer should be

4x^3-x+8

Answer 3

Given:

(X³-8x+2)+(3x³+7x+6)

X³-8x+2+3x³+7x+6

(X³+3x³)-(8x+7x)+(2+6)

4x³-15x+8

Changed:

1) Replace uppercase X with lowercase x in all equations

(x³ - 8x + 2) + (3x³ + 7x + 6)

2) No change

x³ - 8x + 2 + 3x³ + 7x + 6

3) Replace + with - in front of the 7x

(x³ + 3x³) - (8x - 7x) + (2 + 6)

4) Correct answer

4x³ - x + 8

Answer 4

To check your work on these kinds of problems use Substitution and Evaluation.

Let x=1 (unless this would generate a zero in the denominator).

(X³-8x+2)+(3x³+7x+6) becomes (1-8+2)+(3+7+6)=11

4x³ - x + 8 becomes 4-1+8=11.

Quick and easy.