Question

If 3 is a zero of the polynomial x2 + 2x - a. Find a​

Answer 1

Answer:

3 is the zero of the polynomial, then f(3) = 0

f(3) = 0

(3²)+2(3)-a= 0

9 + 6 - a= 0

15 - a = 0 .

15 = a.

Now, The polynomial is x² + 2x - 15 .

Factorising the polynomial,

x² + 2x - 15

x² + 5x - 3x - 15

x ( x + 5 ) - 3 ( x + 5 )

( x + 5 ) ( x - 3 )

Therefore , x²+2x-15 = (x+5)(x-3)

Zero of the polynomial : The value of the variable for which polynomial is 0

( x + 5 ) ( x - 3 ) = 0

x = -5 , x = 3 .

Therefore, the other zero is -5 .

Answer 2

${\huge{\star{\red{\bold{\boxed{\boxed{Answer}}}}}}}{\huge{\star}}$

${\pink{\huge{a=15}}}$

⭐${\blue{\huge{Explanation}}}$⭐

If 3 is the zero of p(x) , then p(3) = 0. Take p(3) and find the value of a from that equation.

p(x) = x² + 2x - a

p(3) = 3² + 2(3) - a

p(3) = 15 - a

Now, p(3) = 0, so,

15 - a = 0

a = 15

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