How do you figure out positive and negative in math?

Answer 1

That is a very good question. Let me break it down by Multiplication, Division, Addition, and finally Subtraction.

Multiplication:

Negative x Positive = Negative

Ex: -4 x 5 = -20

Positive x Positive = Positive

Ex: 5 x 4 = 20

Negative x Negative = Positive.

Ex: -5 x -4 = 20

Division:

Negative ÷ Positive = Negative

Ex: -5 ÷ 5 = -1

Positive ÷ Positive = Positive

Ex: 5 ÷ 5 = 1

Negative ÷ Negative = Positive

Ex: -5 ÷ -5 = 1

Addition:

Positive + Positive = Positive

Ex: 20 + 20 = 40

Positive + Negative = Takes the sign of the greater number.

Ex: 50 + -60 = -10

Ex: 60 + -50 = 10

Negative + Negative = Negative

Ex: -50 + -20 = -70

Subtraction:

Positive - Positive = Positive

Ex: 10 - 5 = 5

Negative - Positive = Negative

Ex: -7 - 1 = -8

Negative - Negative = Takes the sign of the greater number

Ex: -5 - (-4) = -1

Ex: -6 - (-7) = 1

Explanation: Remember in Multiplication a Negative x Negative = Positive? Well look at the signs in the last example. In -5 - (-4) the minus sign is being multiplied to the -4. So -1 x -4 = 4. Rewrite it. -5 + 4 = -1. In the second example the sign rule applies. -6 - (-7), Negative x Negative = Positive. So -1 x -7 = 7. Therefore 7 + (-6) = 1.

Remember the ultimate algebra rule. Please Excuse My Dear Aunt Sally.

Parentheses

Exponents

Multiplication

Division

Addition

Subtraction

This is called the Order of Operations.