# Basic Algebra/Introduction to Basic Algebra Ideas/Working With Negative Numbers

Positive
Negative

## Lesson

### Negative Numbers

A positive number is a number greater than zero.

A negative number is a number less than zero. You make a negative number by doing the negative operation on a positive number. You use the " – " sign for the negative operation. This sign is the same you use for subtracting.

### Adding and Subtracting

Adding a negative number is the same as subtracting a positive number.

• $7+(-4)=7-4$ • $x+(-y)=x-y$ Subtracting a negative number is the same as adding a positive number.

• $7-(-4)=7+4$ • $x-(-y)=x+y$ ### Multiplying and Dividing

Multiplying a negative number by a positive number, or a positive number by a negative number makes the result negative.

• $(-2)\times 3=-6$ • $2\times (-3)=-6$ Multiplying a negative number by a negative number makes the result positive.

• $(-2)\times (-3)=6$ You do the same for dividing.

• $(-6)\div 3=-2$ • $6\div (-3)=-2$ • $(-6)\div (-3)=2$ ### Exponentiating

Exponentiating a negative number to an even (a number you can divide by two) power makes the result positive.

• $(-3)^{2}=9$ • $(-x)^{2}=(-x)\times (-x)=x^{2}$ Exponentiating a negative number to an odd (a number you can not divide by two) power makes the result negative.

• $(-2)^{3}=-8$ • $(-x)^{3}=(-x)\times (-x)\times (-x)=x^{2}\times (-x)=-x^{3}$ ### Order of Operations

The negative operation has the same precedence as multiplying and dividing.

• $3+8\div 4=3+2=5$ • $-3^{2}=-(3\times 3)=-9$ • $(-3)^{2}=(-3)\times (-3)=9$ ## Example Problems

• $4+(-4)=0$ • $4+(-7)=-3$ • $0+(-2)=-2$ • $-5+7-2\times (-4)=10$ ## Practice Problems

1

 $6+(-3)=$ 2

 $3+(-9)=$ 3

 $-4\times 4=$ 4

 $4\times (-9)=$ 5

 $-2\times (-4)=$ 6

 ${\frac {-25}{5^{2}}}=$ 7

 $-4\div 2=$ « Basic AlgebraWorking With Negative Numbers » Variables and Expressions Solving Equations Using Properties of Mathematics