已知：x=根号8+根号7分之根号8－根号7,y=根号8－根号7分之根号8+根号7,求根号x+根号y分之x+y+2倍根号...已知：x=根号8+根号7分之根号8－根号7,y=根号8－根号7分之根号8+根号7,求根号x+根号y分之x+y

Question

已知：x=根号8+根号7分之根号8－根号7,y=根号8－根号7分之根号8+根号7,求根号x+根号y分之x+y+2倍根号...
已知：x=根号8+根号7分之根号8－根号7,y=根号8－根号7分之根号8+根号7,求根号x+根号y分之x+y+2倍根号xy的值.

Answer 1

X=(√8-√7)/(√8+√7)=(√8-√7)²;
y=(√8+√7)/(√8-√7)=(√8+√7)².
则:(x+y+2√xy)/(√x+√y)
=(√x+√y)²/(√x+√y)
=√x+√y
=√(√8-√7)²+√(√8+√7)²
=(√8-√7)+(√8+√7)
=4√2.