ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
SAT Math: Solving a Rational Equation through Common Denominators 5 Views
Share It!
Description:
What are the value(s) of x in the rational equation above?
Transcript
- 00:00
Yeah Whoa Okay I say t mash bumpers and other
- 00:05
weird equation for you here We got this thing and
- 00:08
one of racks wanted Teo name exposed to what The
- 00:11
values of acts in the rational equation above All right
- 00:17
So rational meaning X is not zero nor negative too
Full Transcript
- 00:20
Right Okay well let's think about this Would it be
- 00:22
irrational to a skip this rational equation question Probably because
- 00:27
it's much simpler than it looks Let's start by writing
- 00:29
every term with a common denominator because fractions loved to
- 00:32
get closer together So let's think about this We're going
- 00:35
to multiply out X plus two on both sides of
- 00:38
this thing and then x over exxon this thing and
- 00:41
then x over X I guess Yeah on this thing
- 00:43
So that gives us as the denominator extends quantity X
- 00:46
plus two and the numerator looks like this So then
- 00:49
we have What is that X plus two plus Acts
- 00:53
over X 20 exposed to and and that equals negative
- 00:56
two acts over this thing and then we can rewrite
- 00:58
it again as two x plus two over x ten
- 01:02
twenty flew and then equals negative to activate All right
- 01:05
so a few operations with fractions and our question becomes
- 01:08
so much easier to deal with The denominators of these
- 01:11
two fractions are exactly the same So the numerator Sze
- 01:13
must equal as well It's a big trick there You
- 01:16
have to know you crossed this whole bottom thing out
- 01:19
and it gives you two X plus two equals negative
- 01:21
to X Well then four Acts If you add 2
- 01:24
exit both sides and subtract two from their equals native
- 01:27
to so X is negative to force or negative one
- 01:31
half Well it's like he's our answer but because this
- 01:33
is a rational equation we need to check that B
- 01:36
is not an extraneous solution i e One that does
- 01:39
not make the denominator equal to zero We're looking at
- 01:42
the original equation We can see that if Acts were
- 01:44
equal 2:0 or negative too those would be extraneous Welby
- 01:48
doesn't cause any problems so well that's our answer You
- 01:51
got to be careful in these because they'll throw curveballs
- 01:53
like at you all day long If you divide by
- 01:55
zero it has to be undefined If it's not well 00:01:58.49 --> [endTime] it's probably wrong
Up Next
In the equation above, if a, b, and c are all constants, what is c?
Related Videos
SAT Math 1.1 Numbers and Operations. How many combinations of beverage and cereal can be made?
When x = 12, a certain polynomial, y, equals 0. Which of the following must be true about the polynomial y?
SAT Math 1.1 Algebra and Functions. Find an algebraic equation to correspond with the data.
SAT Math 1.1 Geometry and Measurement. What is the circumference of the circle?