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Mathematics 20 Online
OpenStudy (anonymous):

DSDFSDGDSG

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

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?

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)

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

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

OpenStudy (anonymous):

a=1 and b=-4?

jimthompson5910 (jim_thompson5910):

correct

OpenStudy (anonymous):

thank you sooooo much!!!

jimthompson5910 (jim_thompson5910):

you're welcome

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