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OpenStudy (anonymous):
@phi @Compassionate @Loser66 @jim_thompson5910
jimthompson5910 (jim_thompson5910):
plug x = 2 into cx^2+4x to get ???
OpenStudy (anonymous):
4c+8
jimthompson5910 (jim_thompson5910):
plug x = 2 into x^3-cx to get ???
OpenStudy (anonymous):
8-2c
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jimthompson5910 (jim_thompson5910):
set the two expressions equal to each other and solve for c
OpenStudy (anonymous):
c=0
OpenStudy (anonymous):
thank you so much! could you help me with a similar problem? i think i now know how to do it but i could still use help
jimthompson5910 (jim_thompson5910):
go ahead
OpenStudy (anonymous):
so would you plug in 2 for the first two equations and plug in 3 into the second two?
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jimthompson5910 (jim_thompson5910):
you are correct
OpenStudy (anonymous):
ok. the first equation is undefined at 2
jimthompson5910 (jim_thompson5910):
actually, yeah I just realized that lol, hmm let me think
jimthompson5910 (jim_thompson5910):
no wait
jimthompson5910 (jim_thompson5910):
x^2 - 4 factors to (x-2)(x+2)
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jimthompson5910 (jim_thompson5910):
then the x-2 terms will cancel
OpenStudy (anonymous):
but its still undefined. that doesnt change
jimthompson5910 (jim_thompson5910):
there's a removable discontinuity at x = 2 for (x^2-4)/(x-2)
OpenStudy (anonymous):
yes. there is
jimthompson5910 (jim_thompson5910):
basically there's a hole there
to make things continuous, we need to see what values of a & b will make the second piece connect to the first
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jimthompson5910 (jim_thompson5910):
(x^2-4)/(x-2) simplifies to x+2
so when x = 2, x+2 becomes 4
jimthompson5910 (jim_thompson5910):
then we plug x = 2 into ax^2-bx-8 to get 4a-2b-8
jimthompson5910 (jim_thompson5910):
We want this to equal 4 so the first and second pieces connect
4a-2b-8 = 4
jimthompson5910 (jim_thompson5910):
Now we plug x = 3 into the second piece to go from ax^2-bx-8 to 9a-3b-8
and we plug x = 3 into the third piece to go from 6x-a+b to 18-a+b
we can now say
9a-3b-8 = 18-a+b
jimthompson5910 (jim_thompson5910):
so the goal is to now solve this system of equations
4a-2b-8 = 4
9a-3b-8 = 18-a+b
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