what should be added to y^2,+4xy to make it a perfect sq Question what should be added to y^2,+4xy to make it a perfect sq in progress 0 Math Vivian 16 mins 2021-10-13T02:16:59+00:00 2021-10-13T02:16:59+00:00 1 Answer 0 views 0

## Answers ( )

Answer:By adding four we can make it perfect square

4

x

2

+

8

x

+

4

(

2

x

)

2

+

2

⋅

2

x

⋅

2

+

(

2

)

2

(

2

x

+

2

)

2

Thus it becomes a perfect square

But how do we get to this answer without any guess , here’s the role of discriminant.

Any quadratic equation is of form

a

x

2

+

b

x

+

c

=

0

Here , discriminant

(

d

)

=

b

2

−

4

a

c

For perfect squares it is

0

So , we get

0

=

8

2

−

4

×

4

×

c

64

=

16

c

c

=

4

That’s the answer