SAT Math: Isolating a Variable with Fractions and a Little Common Sense

Given the function shown above, if f(x) = 2, which of the following expressions represents c?

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SAT MathNumbers and Operations
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Test PrepSAT Math

Transcript

00:17

Cee We knew this problem the easy way or the

00:20

hard way Oh let's do it the easy way says

00:23

everyone ever The hard way would be to approach this

00:25

problem by finding a common denominator and then start adding

00:29

the two fraction together right away But here's the deal

00:32

See only shows up in one of the fractions so

00:35

we can just isolate that fraction on one side of

00:37

the equation Then get rid of everything that isn't wet

00:40

Yeah everything that is in the sea Okay Don't forget

00:44

that F of X equals two right here so we're

00:46

going to rewrite it to equals this and we're going

00:48

to move things around a little bit Subtract two from

00:51

this side add back See overexposed four on this side

00:54

Now these are two fractions we'd like to put together

00:56

so we're going to a factory in an X plus

00:59

two there And then Well it gets us come and

01:01

denominator there And then we've got C over expose for

01:04

is one minus two x minus four over exposed to

01:07

We're just multiplying out to there to the two exit

01:09

on the four Okay And then what do we have

01:11

Let's say we've got to see Overexpose four is negative

01:15

Two x minus three over X plus two Okay Now

01:17

to blast that X plus four out of there leaving

01:20

sweet sweet see behind What does that get us Well

01:22

let's say we got the quantity Negative two ex money

01:25

three times quantity expose for over exposed to And let's

01:29

get rid of the bottom parentheses there on the rewrite

01:31

and well it looks like that Well here's our answer

01:34

It's right there You see equals negative quantity to explosive

01:37

Ream him how it's done