Question

Okay so I need some help. Im trying to help my brother on his homework, but I forget how to solve these inequalities.

-4d > 8 and 2d > -6

Answer 1

alright so the first thing you need to do is solve it as you would any other equation.

let's ignore the inequality for now and replace it with an equal sign.

can you solve this for d?

-4d = 8

Answer 2

You would divide by -4.

Answer 3

so you would end up getting

d = -4

now whenever you divide by a negative number, you need to switch the direction of the inequality sign.

so before it was

d > -4

should be

d< -4

now let's try to understand this.

our answer d < -4 means that any number less than -4 will make the above problem of

-4d>8 true.

let's test it.

say if we put in -5

-4*-5 = 20

20 > 8 of course 20 is greater than 8, so we know right away that

d<-4 is our solution.

Answer 4

Wouldn't it be d < -2 ? Since it was -4d> 8 . So divide 8 by -4 and get -2.

Answer 5

yep :) I was reading this other article, got distracted but you get the idea right?

Answer 6

if you divide by a - number you need to switch the sign of the inequality

Answer 7

And then the next equation is 2d > -6.

So divide by 2 which would give me d>-3.

And yeah I understand what you're saying.

Answer 8

cool so let's check that answer you just got

Answer 9

d > -3

means d is greater than -3

so let's try -2

2(-2) > -6

-4 > - 6

that's true

-4 is greater than -6 because -4 is closer to zero than -6 so that's true.

Answer 10

Okay I understand that. But I'm confused by the "and" part. How does that fit in?

Answer 11

hey what do you mean by the "and" part?

Answer 12

@CamoGreen883

Answer 13

The equation is -4d > 8 and 2d > -6.

Answer 14

Those are two separate in-equalities solve each separately as we did

Answer 15

Ohhh okay. Thank you.