How do you multiply 7\frac { 1} { 2} \cdot ( - 7\frac { 1} { 5} )712(715)?

3 Answers
Sep 29, 2017

See a solution process below:

Explanation:

First, convert each mixed number to an improper fraction:

7 1/2 * (-7 1/5) =>712(715)

(7 + 1/2) * (-(7 + 1/5)) =>(7+12)((7+15))

([2/2 * 7] + 1/2) * (-([5/5 * 7] + 1/5)) =>([227]+12)(([557]+15))

(14/2 + 1/2) * (-(35/5 + 1/5)) =>(142+12)((355+15))

(14 + 1)/2 * (-(35 + 1)/5) =>14+12(35+15)

15/2 * (-36/5)152(365)

Now, multiply the numerators over the denominators multiplied:

-(15 * 36)/(2 * 5) =>153625

-(color(red)(cancel(color(black)(15)))3 * color(green)(cancel(color(black)(36)))18)/(color(green)(cancel(color(black)(2)))1 * color(red)(cancel(color(black)(5)))1) =>

-(3 * 18)/(1 * 1) =>

-54/1 =>

-54

You need to convert to improper fractions, then multiply across.

Explanation:

To convert to an improper fraction, you need to multiply the whole number (7 in both fractions) with the denominator. The answer you get is then ADDED to the numerator.

The problem should look like this:

7 1/2 * (- 7 1/5) = (7 * 2 + 1)/2 * (- (7 ( 5 + 1))/5)

= 15/2 * (-36/5)

After you do this, you can then multiply across: numerator times numerator, and denominator times denominator.

= (15 * (-36))/(2 * 5) = 5 * (-18)

Because the second fraction is a negative, the answer will be negative.

Sep 29, 2017

Convert it into standard form.
7*1/2= ((2*7)+1)/2=15/2

-7*1/5= -((5*7)+1)/2=-36/5

Now, Multiply:
15/2*-36/5=(15*(-36))/(2*5)
=-540/10

=color(blue)(-54)