Question

已知(x-y)的平方根是±√2,(2x+5y-3/8)的立方根是-3/2,求x²-y²的算术平方根

Answer 1

x-y=(√2)²

2x+5y- 3/8=(-3/2)³

整理,得

x-y=2 (1)

2x+5y=-3 (2)

(1)×5+(2)

7x=7

x=1

代入(1)

y=x-2=1-2=-1

√(x²-y²)=√[1²-(-1)²]=√(1-1)=0