Question 124614This question is from textbook
: Would someone be able to help me with this problem?
The solution to the inequality x^3-4x^2-x+4(
My answer options are:
a.[1,4]
b.(-infinity,-1]U[1,4]
c.[4,infinity)
d.[-1,1]U[4,infinity)
I thought the answer was a.,is this correct? Please help as soon as possible!!!
This question is from textbook
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The solution to the inequality x^3-4x^2-x+4(
Factor to get:
(x+1)(x-1)(x-4)<=0
The zeroes are x = -1, x=1, x=4
Draw a number line; Plot those x-values.
Test a point in each of the resulting intervals to see where the solutions are.
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If x=-2 you get: (-)(-)(-) < 0 ; true, solutions in (-inf,-1}
Since only "b" contains that information, check x=2
If x = 2 you get: (+)(+)(-) <0; true, solutions in [1,4]
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Ans: "b"
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Cheers,
Stan H.
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My answer options are:
a.[1,4]
b.(-infinity,-1]U[1,4]
c.[4,infinity)
d.[-1,1]U[4,infinity)
I thought the answer was a.,is this correct?
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