Question

Identify the 3 errors:

(2x32x2 + 5x - 1) - (8x3 - 10x2 - 2x + 4) = -6x3 - 8x2 + 3x + 3
Fill in the corrected numbers and + or - signs: x3 = x² = X =

Answer 1

-6x³ + 8x² + 7x - 5

Explanation:

Let's do the subtraction correctly.

(2x³ - 2x² + 5x - 1) - (8x³ - 10x² - 2x + 4) =

Remove the first set of parentheses since they are unnecessary.

= 2x³ - 2x² + 5x - 1 - (8x³ - 10x² - 2x + 4)

To remove the second set of parentheses, think of the negative sign to its left as being a -1. When you distribute that -1, all signs inside the second set of parentheses change.

= 2x³ - 2x² + 5x - 1 - 8x³ + 10x² + 2x - 4

Now group like terms together.

= 2x³ - 8x³ - 2x² + 10x² + 5x + 2x - 1 - 4

Combine like terms.

= -6x³ + 8x² + 7x - 5

The given incorrect sum is:

-6x³ - 8x² + 3x + 3

The three errors are -8x², 3x, 3.

The correct sum is -6x³ + 8x² + 7x - 5