Question

9. What must be added to 5x3 - 2x2 + 3x + 7 to get 7x3 + 7x - 5?​

Answer 1

Step-by-step explanation:

Let y be the "thing" to add to 5x^3 - 2x^2 + 6x +7 to equal x^3 + 3x^2 -x +1:

Therefore:

5x^3 - 2x^2 + 6x +7 + y = x^3 + 3x^2 - x + 1

Step 1: Rearrange equation and solve for y

y = x^3 + 3x^2 - x + 1 - (5x^3 - 2x^2 + 6x +7)

Step 2: Carry out multiplication of -1

y = x^3 + 3x^2 - x + 1 - (5x^3 - 2x^2 + 6x +7)

y = x^3 + 3x^2 - x + 1 - 5x^3 + 2x^2 - 6x - 7

Step 3: Rearrange equation

y = x^3 - 5x^3 + 3x^2 + 2x^2 -x - 6x + 1 -7

Step 4: Simplify equation by

y = (1 - 5)x^3 + (3 + 2)x^2 + (-1 -6)x + (1–7)

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

Therefore, if you add -4x^3 + 5x^2 - 7x -6 to 5x^3 - 2x^2 + 6x +7, you'll get x^3 + 3x^2 -x +1.