Question

2. A number added to twice its square, then
the result is 21. A quadratic equation of this
situation is
(1 point )​

Answer 1

Answer:

Let the number be x

Given

x is added to twice its x

2

gives 21

2x

2

+x=21

⟹2x

2

+x−21=0

⟹2x

2

+7x−6x−21=0

⟹x(2x+7)−3(2x+7)=0

⟹(x−3)(2x+7)=0

⟹x=3,−

2

7

The number is 3,−

2

7

Answer 2

Answer:

this is the required equation

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