Q. Practice problemsFind the zeros of the Folynomial functionsf(x)=x3+8x2+11x−20
Identify Obvious Factors: Look for any obvious factors of the polynomial.Try plugging in simple values like x=1, x=−1 to see if they are zeros.f(1)=13+8⋅12+11⋅1−20=1+8+11−20=0, so x=1 is a zero.
Use Synthetic Division: Use synthetic division or long division to divide the polynomial by (x−1).Divide f(x) by (x−1) to find the other factors.(x−1)∣x3+8x2+11x−20 | x2+9x+20The quotient is x2+9x+20.
Factor Quadratic Equation: Factor the quadratic equation x2+9x+20.Look for two numbers that multiply to 20 and add up to 9.The numbers are 5 and 4, so the factors are (x+5) and (x+4).
Solve for Zeros: Set each factor equal to zero and solve for x.x−1=0 gives x=1x+5=0 gives x=−5x+4=0 gives x=−4
List All Zeros: Write down all the zeros of the polynomial.The zeros are x=1, x=−5, and x=−4.
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