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For which values of z in the function f(z) positive? F(z) = (z-7)(z+5)

For which values of z in the function f(z) positive? F(z) = (z-7)(z+5)-example-1
User Carly
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1 Answer

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Given:


f(z)=(z-7)(z+5)

Multiply of two number is positive that mean both number is positive or both number is negative so:

For both positive :


z>7

For both negative :


z<-5

For function is positive


\begin{gathered} (-\infty,-5)\cup(7,\infty) \\ or \\ -5>z>7 \end{gathered}

(B)

for function negative:

One factor is positive and another factor is negative:

[tex]-5
User Nikola Irinchev
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