Step 1: Use the Factor Theorem to confirm the given root.
The problem states that h(−21)=0. According to the Factor Theorem, if h(c)=0, then (x−c) is a factor of h(x).
Here, c=−21, so (x−(−21))=(x+21) is a factor.
To avoid fractions, we can multiply this factor by 2, which means (2x+1) is also a factor.
Let's verify h(−21):
h(−21)=4(−21)3+4(−21)2+73(−21)+36
h(−21)=4(−81)+4(41)−273+36
h(−21)=−21+1−273+36
h(−21)=21−273+36
h(−21)=−272+36
h(−21)=−36+36=0
This confirms that (2x+1) is a factor of h(x).
Step 2: Divide the polynomial h(x) by (2x+1) to find the other factor.
We can use polynomial long division:
\multicolumn2r2x2\cline2−52x+1\multicolumn2r−(4x3\cline2−3\multicolumn2r0\multicolumn2r\cline3−4\multicolumn2r\multicolumn2r\cline4−5\multicolumn2r+x4x3+2x2)2x2−(2x20+36+4x2+73x+x)72x−(72x0+73x+36+36)0+36
The quotient is 2x2+x+36.
So, h(x)=(2x+1)(2x2+x+36).
Step 3: Attempt to factor the quadratic term 2x2+x+36.
We check the discriminant Δ=b2−4ac for the quadratic ax2+bx+c.
For 2x2+x+36, we have a=2, b=1, c=36.
Δ=(1)2−4(2)(36)
Δ=1−288
Δ=−287
Since the discriminant Δ<0, the quadratic factor 2x2+x+36 has no real roots and cannot be factored further into linear factors with real coefficients.
Therefore, the factorization of h(x) over real numbers is:
(2x+1)(2x2+x+36)
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