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In the expression below, a is an integer. 12^3+ax-20 if 3x+4 is a factor of the expession above, what is the value of a

User Peadar
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1 Answer

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Our function is:


f(x)=12^3+ax-20

Now, if
3x+4 is a factor of
f(x) then
x=(-4)/(3) must satisfy the equation:

So,
f((-4)/(3) )=0

Putting
x=(-4)/(3)

We get,


f((-4)/(3) )=12^3+a((-4)/(3) )-20=0


12^3+(-4)/(3) a-20=0


(-4)/(3) a=20-12^3=20-1708


a=-1708 * (-3)/(4) =1281

So, the value of 'a' for the given expression is 1281.

User Mezm
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