Lesya P.

asked • 09/01/23

Pre calculus, 12 grade

Draw the graph f(x)= (x+2)^3(x-1), find zero and their multiplicity.

1 Expert Answer

By:

Nikolai O.

I believe that the multiplicity for -2 is 3, not 1. Multiplicity refers to the number of times a zero appears in the factorization of the f(x). The polynomial here is: (x+2)^3 * (x-1) Which is equal to: (x+2) * (x+2) * (x+2) * (x+1) Thus, the zero x = -2 "appears" in the factored form of f(x) three times. Thus, x = -2 has a multiplicity of three, not one. Similarly, the zero x = -1 "appears" in the factored form of f(x) once. Thus, x = -1 has a multiplicity of one. Side note: The multiplicity of all zeros in a polynomial must add up to its degree. f(x) in expanded form is: (x+2)^3 * (x+1) = x^4 + 7x^3 + 18x^2 + 20x + 8 Since the highest term is x^4, f(x) is a fourth-degree polynomial. Notice that the zeros have a multiplicity of the zeros of f(x) are: x = -2 <- Multiplicity of three x = 1 <- Multiplicity of one Therefore, the multiplicity "add up" to four. This is a great way to check whether or not your answer is correct.
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09/01/23

Doug C.

And since the multiplicity of each zero is odd, the graph &quot;passes through&quot; the x-axis at those zeros. Try changing the exponent to an even integer on one or both factors to see that the graph &quot;bounces off&quot; the x-axis at zeros with even multiplicity. Then try raising the exponents to higher multiplicity (both odd and even) to see the graph flatten in the vicinity of the zeros: desmos.com/calculator/6lhf6bnf7e
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09/01/23

Brenda D.

tutor
Thanks and yes the multiplicity of x=-2 is 3 it appears once in the graph but per the exponent it is still (x+2)(x+2)(x+2). I will update
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09/02/23

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