I recently took a practice test and am now reviewing my mistakes. I came across this question and can not figure it out.
Which of the following is NOT a factor of z^5 -16z
A) z^2 - 1
B) z^2 - 4
C) z +2
D) z
E) z - 2
The correct answer is A
Any explanation of how to do this problem is greatly appreciated :)
Which of the following is NOT a factor of z^5 -16z
A) z^2 - 1
B) z^2 - 4
C) z +2
D) z
E) z - 2
The correct answer is A
Any explanation of how to do this problem is greatly appreciated :)
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This is readily factored.
z^5 - 16z = z(z^4 - 16) = z(z² - 4)(z² + 4) = z(z - 2)(z + 2)(z² + 4).
Compare all the options to these various stages of factorizations. You see that A is the only expression that does not appear.
P.S. What you need as prior knowledge is some familiarity with factoring including the difference of square a² - b² = (a - b)(a + b).
z^5 - 16z = z(z^4 - 16) = z(z² - 4)(z² + 4) = z(z - 2)(z + 2)(z² + 4).
Compare all the options to these various stages of factorizations. You see that A is the only expression that does not appear.
P.S. What you need as prior knowledge is some familiarity with factoring including the difference of square a² - b² = (a - b)(a + b).