Question

If x-y=7 and xy= 9 find the value of x⁴+y⁴

Answer 1

ANSWER:

(x-y)²=7²

(x-y)²= x²+y²-2xy

49=x²+y²-2*9(value of xy=9)

49=x²+y²-18

49+18=x²+y²

67=x²+y²

67²=(x²+y²)²

4489=x⁴+y⁴+2x²y²

4489=x⁴+y⁴+2*67

4489=x⁴+y⁴+134

4489-134=x⁴+y⁴

4355=x⁴+y⁴

hope it helps....