Question

if x+y=15and xy= 20, then find the value of x square + y square. ​

Answer 1

Answer:

X+y= 15

xy= 20

(x+y)^2= 15^2

x^2+y^2+2xy= 225

x^2+y^2+2×20= 225

x^2+y^2+40=225

x^2+y^2= 225-40

x^2+y^2= 185

Answer 2

Answer:

185

Step-by-step explanation:

x + y = 15

Squaring both sides

${(x + y)}^{2} = {15}^{2}$

${x}^{2} + {y}^{2} + 2xy = 225$

${x}^{2} + {y}^{2} = 225 - 2xy$

Putting xy = 20 from question.

We get,

${x}^{2} + {y}^{2} = 225 - 2(20)$

${x}^{2} + {y}^{2} = 225 - 40$

${x}^{2} + {y}^{2} = 185$

HOPE IT HELPS YOU