Math+Test+Unit+5+-+Multiplying+&+Dividing+Fractions

=Math Chpt. 5 Study Guide=

Reciprocal (Lesson 5-3)

 * //Definition:// Two fractions whose product = 1
 * //Example//: 4/9 and 9/4 are reciprocals because 4/9 x 9/4 = 1
 * The numerator (top number) and denominator (bottom number) are switched when you find the //**reciprocal**.//
 * Use it when you are trying to divide by a fraction. Remember this by thinking "Invert and multiply" Like: 3/5 ÷ 1/3 could be solved by doing 3/5 times the reciprocal of 1/3 which is 3/1. Note: "Invert and multiply" is only used for dividing fractions/mixed numbers, not multiplying.

To divide a fraction by a fraction (Lesson 5-3)

 * You don't have to have common denominators like when you add and subtract fractions.
 * "Invert and multiply"
 * Multiply the first number (leave it alone!) by the reciprocal of the second number.
 * Example: 9/16 3/4 could be solved by doing 9/16 x 4/3. Cross cancel the 9 and the 3 and the 16 and the 4.
 * You'll get 3x1=3 for the numerator and 4x1=4 for the denominator so that would be the fraction 3/4 in simplest form.
 * To divide a whole number by a fraction you write the whole number into a fraction and that would be blank over 1



Solving Algebraic Fractions Equations by Multiplying (Lesson 5-5)
===First you take the second fraction and you flip it upsidown to get a //reciprocal.// Then since you multiplied on that side you have to multiply the number that it equals by that and you get your answer.===

Divide to find the number of cupcakes in a row to cover the length of the box.

17 1/2 divided by 1 1/4 = 35/2 divided by 5/4 = 35/2 times 4/5 then cross cross cancel which would be 7 times 2 = 14/1 and 14 times 1 = 14 so 14 cupcakes would be your answer to step 1.

Divide to find the number of cupcakes to cover the width of the box. 13 3/4 divided by 1 1/4 = 55/4 divide by 5/4 = 55/4 times 4/5 then cross cancel which would be 11/1 times 1/1 = 11 because 11 times 1 = 11 so your answer to step to would be 11 cupcakes. All togheter would be 11 times 14= 154 cupcakes.


