Cross Multiplying Review -1st Period

Front

What is cross multiplying?

Back

Cross multiplying is a method used to solve proportions. It involves multiplying the numerator of one fraction by the denominator of the other fraction and setting the two products equal to each other.

Front

If \( \frac{a}{b} = \frac{c}{d} \), what is the cross multiplication equation?

Back

The cross multiplication equation is \( a \cdot d = b \cdot c \).

Front

Solve: \( \frac{2}{3} = \frac{x}{9} \)

Back

Cross multiplying gives: \( 2 \cdot 9 = 3 \cdot x \) which simplifies to \( x = 6 \).

Front

What is the first step in solving a proportion using cross multiplication?

Back

The first step is to set the two fractions equal to each other, if they are not already.

Front

Solve: \( \frac{5}{x} = \frac{10}{15} \)

Back

Cross multiplying gives: \( 5 \cdot 15 = 10 \cdot x \) which simplifies to \( x = 7.5 \).

Front

What does it mean if the cross products are equal?

Back

If the cross products are equal, it means that the two fractions are equivalent.

Front

Solve: \( \frac{4}{5} = \frac{y}{20} \)

Back

Cross multiplying gives: \( 4 \cdot 20 = 5 \cdot y \) which simplifies to \( y = 16 \).

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

Solve: \( \frac{3}{4} = \frac{z}{12} \)

Back

Cross multiplying gives: \( 3 \cdot 12 = 4 \cdot z \) which simplifies to \( z = 9 \).

Front

What is the relationship between fractions and proportions?

Back

Fractions can be compared using proportions, which show that two fractions are equal.