Question

if x-y=3 and xy= 15 find the value of x2+y2

Answer 1

Answer:

Step-by-step explanation:

given : x - y = 2, xy=15

(x - y)2 = x2 + y2 - 2xy

22 = x 2 + y2 - 2*15

4 = x2 + y2 - 30

4+30= x2 + y2

x2 + y2=34

so x2 + y2 = 34

(x - y)3 = x3 - y3 -3xy (x - y)

23 = x3 - y3 -3*15(2)

8 = x3 - y3 - 45 * 2

8 = x3 - y3 - 90

8+90= x3 - y3

98 = x3 - y3

x3 - y3 = 98