ACT Math 4.1 Pre-Algebra

ACT Math: Pre-Algebra Drill 4, Problem 1. What could the number described in the video be?

ACT Math	Pre-Algebra
ACT Mathematics	Pre-Algebra
Basic Operations	Absolute Value
Foreign Language	Arabic Subtitled Chinese Subtitled Korean Subtitled Spanish Subtitled
Language	English Language
Pre-Algebra	Absolute value Absolute value and ordering numbers by value
Product Type	ACT Math

00:28

Alright, it's a bit wordy, but let's just write this out in math-ese...

00:36

It says... take the absolute value -- that's these straight line thingies...

00:40

It says "of"... anything "of" is gonna go inside the straight line thingies -- so

00:46

that quantity is...

00:47

2x minus seven.

00:48

See how we did that? Just kinda reversed the order there.

00:53

Then this whole absolute value thing equals 1.

00:56

So what are the numbers that could fulfill this solution for x?

01:00

Well, maybe we just start with the answer set they give us. Could it be A, which is

01:05

negative 4? Well, let's try it.

01:07

We have 2 times negative 4, which is negative 8... then we subtract 7 to get negative 15...

01:13

which, uh... does not equal 1. At least not in the U.S. Choice A can go bye-bye.

01:19

Alright, let's try B... 3.

01:21

2 times 3 is 6; subtract 7 to get negative 1... but we are taking the absolute value

01:26

here so it's... just 1.

01:28

Yeah, 3 works. So the answer is either B or E; we'll have to try C, or 4, to be sure.

01:34

If we plug in 4 for x we get 2 times 4, which is 8... then subtract 7, and we have 1.

01:40

The absolute value thingy doesn't matter for positive numbers so yeah -- x equals 1 here.

01:45

C is true as well, so the answers are both B and C or in this problem...

01:50

...the answer is E.

01:51

As in, "Evil troll."