Question

if 3 is a zero of the polynomial x square +2x _​

Answer 1

Answer:

Let p(x)=x

Let p(x)=x 2

Let p(x)=x 2 +2x−a

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3)

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2 +2(3)−a=0

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2 +2(3)−a=0⇒9+6−a=0

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2 +2(3)−a=0⇒9+6−a=0⇒15−a=0

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2 +2(3)−a=0⇒9+6−a=0⇒15−a=0⇒−a=−15

Let p(x)=x 2 +2x−aAs the zero of this polynomial is 3, we know that p(3)=0.x 2 +2x−a=0Put x=3, we get(3) 2 +2(3)−a=0⇒9+6−a=0⇒15−a=0⇒−a=−15⇒a=15

Answer 2

Answer:

Let p(x)=x

2

+2x−a

As the zero of this polynomial is 3, we know that p(3)=0.

x

2

+2x−a=0

Put x=3, we get

(3)

2

+2(3)−a=0

⇒9+6−a=0

⇒15−a=0

⇒−a=−15

⇒a=15