Question

I seriously need help with these questions. If you could explain to me how to solve these on my own that would be great!
1. Solve for x: -2x + 5 < 7 (1 point)

x > -1
x < -1
x > -6
x < -6
2. Solve for x: 3 - (2x - 5) < -4(x + 2) (1 point)

x < -8
x > -8
x < -3
x > -3
3. Eduardo solved the following inequality and his work is shown below:
-5(x + 4) + 21 ≥ -3 + 4(x - 8)

-5x - 20 + 21 ≥ -3 + 4x - 32

-5x + 1 ≥ 4x - 35

-9x ≥ -36

x ≥ 1

What mistake did Eduardo make in solving the inequality? (2 points)

Answer 1

1. -2x + 5 < 7
Subtract 5 from both sides, inequality side won't change
-2x < 2
Divide both sides by 2, inequality won't change sign now either
-x < 1
Multiply by -1, inequality will change sign
x > -1

2. 3 - (2x - 5) < -4(x + 2)
First, let's simplify it all we can
3 - 2x + 5 < -4x - 8
-2x + 8 < -4x - 8
Divide both sides by 2
-x + 4 < -2x - 4
Subtract 4 from both sides,
-x < -2x - 8
Add x to both sides,
0 < -x - 8
Add 8 to both sides,
8 < -x
Or,
x > -8

3. -5(x + 4) + 21 ≥ -3 + 4(x - 8)
-5x - 20 + 21 ≥ -3 + 4x - 32
-5x + 1 ≥ 4x - 35
-9x ≥ -36
x ≥ 1 <- Right over here, he did something that I don't understand really. Anyone?

Answer 2

Thank you! Do you think that you would be up to helping me with a couple more questions?

Answer 3

Close this question, and post your next question, please and thank you :)

Answer 4

and 3. x <= 1
when dividing by negative numbers in an inequality you change the greater than or less than sign,

Answer 5

Like @shamil98 said, create a new thread.