Question

Find the value of x^2 + y^2 when: (i) x + y = 7 and xy = 10​

Answer 1

${(x + y)}^{2} = {x}^{2} + {y}^{2} + 2xy \\ {x}^{2} + {y}^{2} = {(x + y)}^{2} - 2xy \\ {x}^{2} + {y}^{2} = {7}^{2} - 2(10) \\ {x}^{2} + {y}^{2} = 49 - 20 \\ {x}^{2} + {y}^{2} = 29$

hope it helps

Answer 2

To find : Value of x² + y²

Answer : x² + y²  = 28

Step by step explanation :

We know that,

( x + y )² = x² + y² + 2xy

➡️ x² + y² = ( x + y )² - 2xy

We are given that,

x + y = 7 and  xy = 10

➡️x² + y² = ( 7 )² - 2 ( 10 )

➡️x² + y² = 49 - 20

➡️ x² + y² = 29

Hence,

29 is the required solution.