Question

If 4x2 + y2 = 40 and xy = 6, find the value of 2x + y
​

Answer 1

Step-by-step explanation:

We have,

(2x+y)

2

=(2x)

2

+y

2

+2×2x×y

⇒(2x+y)

2

=(4x

2

+y

2

)+4xy

⇒(2x+y)

2

=40+4×6⇒(2x+y)

2

=64

⇒2x+y=±

64

⇒2x+y=±8

Answer 2

Answer:

8

Step-by-step explanation:

Formula-( a + b )^2= a^2 + 2ab + b^2

4x^2 + y^2= 40

xy = 6

Now the square of  2x + y

( 2x + y )^2 = ( 2x )^2 + 2 × 2x×y + y^2

=4x^2  + 4xy + y^2

= 4x^2 + y^2 + 4xy

= 40 + 4 × 6

( 2x + y )^2 = 40 + 24

= 64

Therefore ,  2x + y = Square root of 64= 8 X 8

Thus answer is 8.

Hope it helps you!!!