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CAHSEE Math 1.4 Algebra I 235 Views
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Description:
CAHSEE Math Algebra I: Drill 1, Problem 4. Which of the following is the solution set to the equation?
Transcript
- 00:03
We’re about to throw an unshmoopy question your way… might want to duck…
- 00:07
Which of the following is the solution set to the equation… the absolute value of 3x – 6 = 21?
- 00:15
And here are the potential answers…
- 00:20
So… what is this question asking?
- 00:22
Can we calculate absolute volume problems with a variable?
Full 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.”
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