CAHSEE Math Algebra I: Drill 1, Problem 4. Which of the following is the solution set to the equation?
|Algebra||One-Variable Equations and Inequalities|
|Algebra I||Solving absolute values|
|CAHSEE Math||Algebra I|
|Functions||Absolute Value Functions|
For starters, let’s just ignore the absolute value piece…
…and solve for 3x minus 6 equals 21.
And add 6 to both sides...
We get 3x equals 27… so x is 9.
That’s if everything’s positive and rosy.
And since we KNOW that one of the solutions has to be 9, we can cross off A and D as potential answers.
The only question left is whether the negative 5 in choice C works as well.
So let’s… give it a spin.
And in this case we DO need to take the absolute value thing into account.
We have 3 times negative 5, which is negative 15 – then subtract 6 and we have negative 21.
But after we take the absolute value… we get positive 21.
And yeah… 21 equals 21… so negative 5 and 9 both work…
…and the answer is C.
As in, “Clear skies ahead.”