MU123: Unit 3 sec 2.3

Unit 3 sec 2.3 Multiplying and dividing fractions

06 November 2015

23:09

Strategy due to multiply fractions

multiplying the numerators together and multiply the denominators together.

Example 5 multiplying fractions

carry out the following fracture multiple occasions stop

(A)

(B) 2 ×

(C)

(D)

Solution

(A)

(B) Here, you can either use this strategy, as is done below, or use the fact that 2 lots 3 seventh is 6 sevenths.

2 ×

(C) ©Here, the number 2 is a factor of the numerator of the 1^st fraction and also a factor of the denominator of the 2^nd fraction, so it is a factor of both the numerator and denominator of the product stop it is easier to cancel factors like this before multiplying

(D) To multiply by a mixed number, 1^st, converted to a top-heavy fraction.

The answer can be left as

if the wish

Your role by doing this can be conveniently described using the idea of reciprocal of a number. The number and its reciprocal multiplied together to give 1. As you can see from example 1, defining the reciprocal of a fraction, you just turn it upside down

Strategy to divide by a fraction

multiply its reciprocal.

Example 6 dividing fractions

carry out the following fraction divisions

(A)

(B)