Read the fraction before calculating: where the denominator is zero, whether each side is already a product, whether there is a root on the bottom or on top.

1Always first: where is a denominator zero?

write down the forbidden values

⟦1⟧

2What is the operation?

a single fraction, with a sum on top or on the bottom

⟦2⟧

equal factors with switched signs

⟦3⟧

product or division of fractions

⟦4⟧→⟦2⟧

addition or subtraction, same denominator

⟦5⟧

addition or subtraction, different denominators

⟦6⟧→⟦5⟧

a fraction inside a fraction

⟦7⟧→⟦4⟧

3Is there a square root?

a lone root on the bottom

⟦8⟧

two terms on the bottom, one with a root

⟦9⟧

a root on top and 0/0

⟦10⟧

rationalized and a factor is left

⟦11⟧→⟦2⟧

!Rationalizing: multiply top and bottom by what?

root	multiply by
√a on the bottom	√a
a + √b on the bottom	a − √b
√a − √b on the bottom	√a + √b
√x − 3 on top	√x + 3

⟦i⟧

Aritmética: frações, sinais e ordem das operações

Caixa de ferramentas

Folha de exercícios