Question

Xy=18 and X square + Y square is equal to 45 find the value of x + Y

Answer 1

Answer:

x + y = 9

Solution:

• Given : xy = 18 , x² + y² = 45
• To find : x + y = ?

We have ;

xy = 18 -------(1)

x² + y² = 45 --------(2)

Also,

We know that ;

=> (x + y)² = x² + 2xy + y²

=> (x + y)² = x² + y² + 2xy

=> (x + y)² = 45 + 2•18

=> (x + y)² = 45 + 36

=> (x + y)² = 81

=> x + y = √81

=> x + y = 9

Hence,

x + y = 9

Answer 2

Answer:

Solution

Step-by-step explanation:

We have ;

xy = 18 -------(1)

x² + y² = 45 --------(2)

Also,

We know that ;

=> (x + y)² = x² + 2xy + y²

=> (x + y)² = x² + y² + 2xy

=> (x + y)² = 45 + 2•18

=> (x + y)² = 45 + 36

=> (x + y)² = 81

=> x + y = √81

=> x + y = 9

Hence,

x + y = 9