If 5 is a zero of x³- 3x² - kx+15, find k.
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Let x³-3x²-kx+15 be a f(x)
Since 5 is a zero of the polynomial, f(5)=0
This means,
5³-3×5²-5×k+15=0
125-75-5k+15=0
125-60=5k
65=5k
Divide both sides by 5
k=13
Since 5 is a zero of the polynomial, f(5)=0
This means,
5³-3×5²-5×k+15=0
125-75-5k+15=0
125-60=5k
65=5k
Divide both sides by 5
k=13
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