Question

Solve.

http://static.k12.com/bank_packages/files/media/mathml_ef759e1d2ede6cf06179a8fe33dcb0aeee3b0747_1.gif

A.
r ≤ –32

B.
r ≥ –32

C.
r ≤ –2

D.
r ≥ –2

Answer 1

These are usually pretty easy. It makes it easier if you pretend that the inequality sign is an equal sign, so: \[-\frac{ r }{ 4 }=8\] What would you do to get r by itself?

Answer 2

take the 4 out?

Answer 3

Yes ma'am! How would you do that?

Answer 4

i dont know :/

Answer 5

Well if you want to cancel out a number, you have to do the opposite. So since its r divided by -4, whats the opposite of division?

Answer 6

multiplication

Answer 7

Mhm! With equations the rule is "what you do to one side you must do to the other. So since we multipy by -4, we have to do the same to the other side. So that gives us \[-\frac{ r }{ 4 }\times-4 = 8(-4)\]
\[r= -32\]

Answer 8

Ohh alright, makes more sense to me now, so would it be A?

Answer 9

Now the rule with inequalities, is that if you ever divide or multiply by a negative, then the sign switches directions. So since we had to multiply by -4, the sign switched from \[\le \to \ge \]

Answer 10

So which would it be?

Answer 11

B :)

Answer 12

You got it :)

Answer 13

Thank you !

Answer 14

My pleasure