Score:0/2 Penaltro 05 alf Question Watch Video If \( f(x)=x^{3}+3 x^{2}-33 x-35 \), which of the following is not a factor of \( f(x) \) ? Answer \( (x+7) \) \( (x-5) \) \( (x+1) \) \( (x+5) \)
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To find which of the given options is not a factor of \( f(x) = x^{3} + 3x^{2} - 33x - 35 \), we can use the Factor Theorem. This theorem states that if \( f(c) = 0 \) for some value \( c \), then \( (x - c) \) is a factor of \( f(x) \). We can evaluate \( f(x) \) for each option: 1. For \( (x+7) \), plug in \( x = -7 \): \( f(-7) = (-7)^{3} + 3(-7)^{2} - 33(-7) - 35 = -343 + 147 + 231 - 35 = 0 \). So, \( (x + 7) \) is a factor. 2. For \( (x-5) \), plug in \( x = 5 \): \( f(5) = (5)^{3} + 3(5)^{2} - 33(5) - 35 = 125 + 75 - 165 - 35 = 0 \). So, \( (x - 5) \) is a factor. 3. For \( (x+1) \), plug in \( x = -1 \): \( f(-1) = (-1)^{3} + 3(-1)^{2} - 33(-1) - 35 = -1 + 3 + 33 - 35 = 0 \). So, \( (x + 1) \) is a factor. 4. For \( (x+5) \), plug in \( x = -5 \): \( f(-5) = (-5)^{3} + 3(-5)^{2} - 33(-5) - 35 = -125 + 75 + 165 - 35 = 80 \). Since \( f(-5) \neq 0 \), \( (x + 5) \) is not a factor. Thus, the option that is not a factor of \( f(x) \) is \( (x + 5) \).