Question

solve (x-3)/(x+1) > 5

I get x < -2 every time, but it doesnt work when I plug it back in. (I plugged in -5)

Answer 1

Multiply both sides times x + 1

x-3 > 5x + 5

-4x > 2

x<-2 You are correct

You choose -5 to check which is correct.

(-5 -3)/(-5 + 1) > 5
-8/-4 >5
2 > 5
That is correct 2 is greater than 5.

Answer 2

Two is greater than five? That's what I do not understand.. Thank you

Answer 3

-4x >8 excuse my typo

x < -2

Lets pretend this is an equation for one minute

(x-3)/(x+1) = 5
Put in the -2
(-2-3/(-2-1) =5
-5/-1 =5
We are correct there...

so.. Since we have an inequality, we have two choices for the final answer.

x> -2 or x > -2

If we choose something larger than -2 will that work?
Lets pick a 2.. ( 2-3)/(2+3) = -1/5 so that is not greater than 5
If we pick a 10 we would have 7/11 which is not greater than 5. We are sure we shouldn't go to the right.

Going to the left..we are having the same problem. You are right 2>5 is wrong.

Try x = -2.5 see how that works.