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TSI Math: Solving a Quadratic Equation through Grouping 2 Views
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Description:
Which of the following values is a root of the equation 10x² = 37x – 7?
- Test Prep / TSI
- Intermediate Algebra and Functions / Quadratic and Other Polynomial Expressions, Equations, and Functions
- TSI / TSI Math
- TSI / TSI Mathematics
- TSI Mathematics / Intermediate Algebra and Functions
- Intermediate Algebra and Functions / Quadratic and Other Polynomial Expressions, Equations, and Functions
- Test Prep / TSI
- TSI Math / Intermediate Algebra and Functions
Transcript
- 00:03
Okay yes i'm ass movers More quadratic ce in polly
- 00:06
and no meals here Which of the following values is
- 00:09
a root of the equation Ten x squared equals thirty
- 00:13
seven x minus seven Okay when you see these things
- 00:18
immediately quad ratify them so we're going to get negative
Full Transcript
- 00:22
Ten x squared plus thirty seven x minus seven is
- 00:24
zero See we've zero fight it then we could use
- 00:27
the quadratic formula here but well we'll solve this equation
- 00:31
by grouping instead It's probably easier when the coefficient of
- 00:34
x squared isn't one like here It's ten or negative
- 00:37
ten Actually the first step is to multiply the coefficient
- 00:39
of x squared by the constant term Well here we
- 00:42
get negative ten times Negative seven which makes positive seventy
- 00:47
Now we need to think of two factors of this
- 00:49
result here for seventy which add up to thirty seven
- 00:52
So what could it be Yeah two times thirty five
- 00:56
is seventy and two plus thirty five is thirty seven
- 01:00
So pretty easy so we can rewrite This is thirty
- 01:02
seven x thing here is to Acts plus 35 acts
- 01:06
that'll help on the fact arising thing here So we're
- 01:09
then gonna factor to acts from the group to simplify
- 01:12
things a tad and we get well to x out
- 01:15
here that multiplies through the negative five x plus one
- 01:19
and then we've got the multiplying by negative seven times
- 01:24
the quantity negative five expose one equal zero we've got
- 01:26
negative five x plus one inside each parentheses here is
- 01:30
very clever very hard to dio Very hard to recognize
- 01:32
but hopefully you got it Okay so yes are factoring
- 01:35
was successful and now we're going to factor out the
- 01:38
negative five x plus one So we get that over
- 01:41
here on the left and then we're going to multiply
- 01:42
it by two x minus seven to get zero Well
- 01:45
the roots can be found by setting each of the
- 01:48
expressions in parentheses equals zero and just solving for x
- 01:51
Right So that gets us negative Five Acts plus 1
- 01:56
equals 0 and while we can subtract one from both
- 02:00
sides there we get negative five x equals negative one
- 02:03
Divide both sides by negative five and we get x
- 02:06
equals a fifth So whoa hold up That happens to
- 02:09
be be so we've technically found our answer However never
- 02:13
let it be said we don't finish what we start
- 02:15
to find the other route I'll do the same with
- 02:17
two x minus seven thereby adding seven on both sides
- 02:20
we get to act Sequel seven in the nexus seven
- 02:22
abs This is a positive value not the negative values
- 02:26
seen in negative seven halves there So give it up
- 02:30
either So the answer is b it's one fifth and 00:02:32.903 --> [endTime] that is in fact a route of that equation
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