Create your own polynomial with a degree of 3 that when divided by x + 2 has a remainder of -4
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myininaya (myininaya):
what do you have so far?
OpenStudy (anonymous):
Nothing, this is to help someone out and this is all she wrote me. I don't know anything about this yet.
myininaya (myininaya):
Well I will tell you some things to start you off
Say we called the polynomial f(x)
We are given f(-2)=-4
myininaya (myininaya):
You need at least two terms.
myininaya (myininaya):
actually you only need one term
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myininaya (myininaya):
or at least one term anyways
myininaya (myininaya):
but whatever the polynomial is you must have x^3 somewhere up in there
myininaya (myininaya):
f(x)=ax^3 <-- so you can choose this
myininaya (myininaya):
f(x)=x^3+b <--this
myininaya (myininaya):
and there are a lot more varieties you can choose
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myininaya (myininaya):
but you must apply the f(-2)=-4
OpenStudy (anonymous):
How does f(-2)=-4 get brought into f(x)=ax^3?
myininaya (myininaya):
f(-2)=-4
means replace x with -2
and when the x=-2 the expression =-4
myininaya (myininaya):
so you can find what that little value a is
OpenStudy (anonymous):
The expression being f(x)=ax^3?
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myininaya (myininaya):
the expression ax^3 was named f(x)
OpenStudy (anonymous):
How would you find a?
myininaya (myininaya):
by using f(-2)=-4
myininaya (myininaya):
this was given in the problem
OpenStudy (anonymous):
What do I do with f(-2)=-4, then?
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myininaya (myininaya):
you apply it to your function we called f
myininaya (myininaya):
remember f(x)=ax^3
myininaya (myininaya):
use f(-2)=-4 to find a
myininaya (myininaya):
f(-2)=-4
says to replace x with -2
and at x=-2 your expression=-4
OpenStudy (anonymous):
Your expression being f(x)=ax^3?
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myininaya (myininaya):
pretend like we have g(x)=9x+c
and I wanted to find c and I was given g(3)=4
g(3)=4 means we have g(3)=9(3)+c=4
so we have 9(3)+c=4
so 27+c=4
then c=4-27=-23
so g(x)=9x-23
myininaya (myininaya):
g(3)=4 means when x=3 the expression we called g is 4
replace x with 3
the expression at x=3, is 4
so we have 9(3)+c=4
---
myininaya (myininaya):
you need to apply f(-2)=-4 to f(x)=ax^3 to find a
OpenStudy (anonymous):
So it'd be f(-2)=a(-2)^3=-4?
myininaya (myininaya):
yep now solve for a
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OpenStudy (anonymous):
-8a=-4, divide the -8
a=0.5 ?
myininaya (myininaya):
yep
you have found a function that works
myininaya (myininaya):
f(x)=.5x^3 or x^3/2
since 1/2=.5
OpenStudy (anonymous):
Yeah. How'd you get the 2nd function?
OpenStudy (anonymous):
f(x)=ax^3 <- that one
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