Pre-Algebra Examples

- 7 x^{2} - 6 x + 9 + - 3 x^{2} - x + 7

$- 7 x^{2} - 6 x + 9 + - 3 x^{2} - x + 7$

Step 1

Replace all occurrences of

+

$+$

-

$-$ with a single

-

$-$ . A plus sign followed by a minus sign has the same mathematical meaning as a single minus sign because

1 \cdot - 1 = - 1

$1 \cdot - 1 = - 1$

- 7 x^{2} - 6 x + 9 - 3 x^{2} - x + 7

$- 7 x^{2} - 6 x + 9 - 3 x^{2} - x + 7$

Step 2

Subtract

3 x^{2}

$3 x^{2}$ from

- 7 x^{2}

$- 7 x^{2}$ .

- 10 x^{2} - 6 x + 9 - x + 7

$- 10 x^{2} - 6 x + 9 - x + 7$

Step 3

Subtract

x

$x$ from

- 6 x

$- 6 x$ .

- 10 x^{2} - 7 x + 9 + 7

$- 10 x^{2} - 7 x + 9 + 7$

Step 4

Add

9

$9$ and

7

$7$ .

- 10 x^{2} - 7 x + 16

$- 10 x^{2} - 7 x + 16$