Mathematics
7 Online
OpenStudy (anonymous):
I have five Algebra II questions... Can someone help me? I'm posting them shortly...
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OpenStudy (anonymous):
OpenStudy (anonymous):
@phi @amistre64 @AccessDenied
OpenStudy (anonymous):
Solve the equations for x. Identify any extraneous solutions. Show all work.
OpenStudy (anonymous):
If somebody can show me one or two of them, I might be able to get the others by myself...
OpenStudy (ivettef365):
to solve the square root, you need to square both sides and then you have
8x+1 = 25
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OpenStudy (ivettef365):
from there can you solve for x
OpenStudy (anonymous):
what's an extraneous solution?
OpenStudy (anonymous):
I got x=3
OpenStudy (ivettef365):
correct
OpenStudy (anonymous):
there aren't any other answers, right?
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OpenStudy (ivettef365):
the next problem, first you subtract 5 from both sides, then you square
OpenStudy (anonymous):
x=43?
OpenStudy (ivettef365):
I get the following, you have
sqrt(x-7) = 11- 5
sqrt(x-7) = 6
OpenStudy (ivettef365):
now square, then you get
x - 7 = 36
OpenStudy (ivettef365):
now solve for x
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OpenStudy (anonymous):
x=43
OpenStudy (ivettef365):
correct, you were right all alone
OpenStudy (anonymous):
are there any extraneous solutions?
OpenStudy (amistre64):
if you get more than 1 possible result, and some test false; the false ones are called extras (extranuous)
OpenStudy (anonymous):
oh okay
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OpenStudy (anonymous):
For #3, do you start by dividing both sides by -4?
OpenStudy (amistre64):
number 5 has the possibilty of getting some extras since you would have to square an x and solve a quadratic
OpenStudy (amistre64):
yes, divide by -4 first
OpenStudy (amistre64):
i might want to amend my thought of extras :)
OpenStudy (anonymous):
x=16?
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OpenStudy (amistre64):
all false solutions are extras; which means that there may be no real solutions
OpenStudy (amistre64):
x=16 is the only thing that might have a chance at working; but the test is false
OpenStudy (anonymous):
so it's the only solution but it's extraneous?
OpenStudy (amistre64):
correct
-4(5) = 20, there is no real solution
OpenStudy (anonymous):
but there is one extraneous?
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OpenStudy (amistre64):
correct
OpenStudy (anonymous):
Number 4 is x=8?
OpenStudy (amistre64):
correct
OpenStudy (anonymous):
I was just double checking my work and it looks like Number 3 has a solution... What did I do wrong?
OpenStudy (anonymous):
Plugging in 16 for X
-4sqrt(16+9)=20
sqrt(16+9)=-5
16+9=25
25=25
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OpenStudy (anonymous):
@amistre64
OpenStudy (anonymous):
I don't understand number 5 at all
OpenStudy (ivettef365):
first subtract the 4 and you get the following
sqrt(x+2) = x - 4
OpenStudy (ivettef365):
then when you square, you have
x+ 2 = (x-4)^2
OpenStudy (ivettef365):
then you solve as follows;
x+2 = (x-4)(x-4)
x+2 = x^2-4x-4x+16
x+2 = x^2-8x+16
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OpenStudy (ivettef365):
can you take it from there
OpenStudy (anonymous):
@ivettef365 what do you do with the x^2?
OpenStudy (ivettef365):
ok, this is what you do
x+2-x-2 = x^2-8x+16-x-2
0 = x^2 -9x+14
OpenStudy (ivettef365):
now x^2-9x+14
(x-7)(x-2) = 0
OpenStudy (ivettef365):
so now to find value of x,
x-7 = 0
x = 7
and
x-2 = 0
x = 2