CAHSEE Math 1.4 Algebra I

CAHSEE Math Algebra I: Drill 1, Problem 4. Which of the following is the solution set to the equation?

AlgebraOne-Variable Equations and Inequalities
Algebra ISolving absolute values
CAHSEE MathAlgebra I
FunctionsAbsolute Value Functions
LanguageEnglish Language

Transcript

00:26

For starters, let’s just ignore the absolute value piece…

00:28

…and solve for 3x minus 6 equals 21.

00:32

And add 6 to both sides...

00:34

We get 3x equals 27… so x is 9.

00:38

That’s if everything’s positive and rosy.

00:40

And since we KNOW that one of the solutions has to be 9, we can cross off A and D as potential answers.

00:47

The only question left is whether the negative 5 in choice C works as well.

00:52

So let’s… give it a spin.

00:54

And in this case we DO need to take the absolute value thing into account.

00:58

We have 3 times negative 5, which is negative 15 – then subtract 6 and we have negative 21.

01:07

But after we take the absolute value… we get positive 21.

01:11

And yeah… 21 equals 21… so negative 5 and 9 both work…

01:17

…and the answer is C.

01:18

As in, “Clear skies ahead.”