Question

If 9x 2 + 25y 2 =181 and xy= -1 find the value of 3x+5y.

Answer 1

Answer:

( 3x + 5y ) = √151

Step-by-step explanation:

Given :

9x² + 25y² = 181

xy = - 1

We know that

( a + b )² = a² + b² + 2ab

Therefore,

( 3x + 5y )² = (3x)² + (5y)² + 2.3x.5y

= 9x² + 25y² + 30xy

= 181 + 30 ( -1 )

= 181 - 30

= 151

As ( 3x + 5y )² = 151

so, ( 3x + 5y ) = √151