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CAHSEE Math 6.1 Algebra and Functions 198 Views
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Description:
Algebra and Functions: Drill Set 6, Problem 1. Solve the inequality.
Transcript
- 00:03
And here's your shmoop du jour.
- 00:05
Solve the inequality 23 - 2x ≥ 25 for x.
- 00:11
Here are the potential answers...
- 00:12
Before we spoil the ending, hit pause and try to solve it yourself.
- 00:17
OK, so, this is another two stepper.
Full Transcript
- 00:19
Which adds the whole "greater than or equal to" twist.
- 00:22
And it can have some nasty twists, so we have to really focus every time we multiply equations
- 00:27
by a negative number...
- 00:29
...as it usually flips the "greater than" thingy around.
- 00:32
To solve -- for starters -- let's subtract 23 from both sides to isolate x...
- 00:36
...and we get that negative 2x is greater than or equal to 25 minus 23 or... 2.
- 00:43
Now let's just clean up x by dividing both sides by 2
- 00:45
and we have... negative x is greater than or equal to 1.
- 00:49
But now comes the twist. We have to divide both sides by negative one because we're
- 00:54
solving for x, not its evil twin.
- 00:57
Anyway, when we divide (or multiply) by a negative number, we have to flip the "greater
- 01:01
than" thingy so NOW we have...
- 01:04
...x is LESS THAN or equal to negative 1... and the answer is A.
- 01:08
It's worth noting that if we hadn't noticed the twist, we would have wound up with Answer B.
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