How do you solve $\frac{- 3}{x + 7} = \frac{8}{x - 4}$ $\frac { - 3} { x + 7} = \frac { 8} { x - 4}$ ?

Question

How do you solve $\frac{- 3}{x + 7} = \frac{8}{x - 4}$ $\frac { - 3} { x + 7} = \frac { 8} { x - 4}$ ?

2 Answers

Impact of this question

1481 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-06T04:53:21

$x = 4$ $x=4$

Explanation:

$- 3 (x - 4) = 8 (x - 7)$ $-3(x-4)=8(x-7)$
$- 3 x + 12 = 8 x + 56$ $-3x+12=8x+56$
$12 - 56 = 8 x + 3 x$ $12-56=8x+3x$
$- 44 = 11 x$ $-44=11x$
$x = - \frac{44}{11}$ $x=-44/11$
$x = - \frac{44}{11}$ $x=-44/11$

here x can never be 0 or -7 as these can make denominators zero

Answer 2 · 2016-11-06T05:06:55

$x = - 4$ $x=-4$

Explanation:

$\frac{- 3}{x + 7} = \frac{8}{x - 4}$ $(-3)/(x+7)=8/(x-4)$

Cross multiply.

$- 3 (x - 4) = 8 (x + 7)$ $-3(x-4)=8(x+7)$

Expand both sides.

$- 3 x + 12 = 8 x + 56$ $-3x+12=8x+56$

Add $3 x$ $3x$ to both sides.

$12 = 8 x + 56 + 3 x$ $12=8x+56+3x$

$12 = 11 x + 56$ $12=11x+56$

Subtract $56$ $56$ from both sides.

$12 - 56 = 11 x$ $12-56=11x$

$- 44 = 11 x$ $-44=11x$

Divide both sides by $11$ $11$ .

$- \frac{44}{11} = x$ $-44/11=x$

$- 4 = x$ $-4=x$

Switch sides.

$x = - 4$ $x=-4$

Science

Math

Humanities

... and beyond

How do you solve $\frac{- 3}{x + 7} = \frac{8}{x - 4}$ $\frac { - 3} { x + 7} = \frac { 8} { x - 4}$ ?

2 Answers

Explanation:

Explanation:

Related questions

Impact of this question

Science

Math

Humanities

... and beyond

How do you solve −3x+7=8x−4\frac { - 3} { x + 7} = \frac { 8} { x - 4}?

2 Answers

Explanation:

Explanation:

Related questions

Impact of this question

How do you solve $\frac{- 3}{x + 7} = \frac{8}{x - 4}$ $\frac { - 3} { x + 7} = \frac { 8} { x - 4}$ ?