Question

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

Answer 1

See a solution process below:

Explanation:

First, convert each mixed number to an improper fraction:

`7 1/2 * (-7 1/5) =>`

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

`([2/2 * 7] + 1/2) * (-([5/5 * 7] + 1/5)) =>`

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

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

`15/2 * (-36/5)`

Now, multiply the numerators over the denominators multiplied:

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

`-(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`

Answer 2

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.

Answer 3

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)`