Question

当X=二分之一,Y=8时,求(X—4Y)/(根号X—2倍根号Y)—(X+Y+2倍根号XY)/(X+根号XY)/(根号X/

Answer 1

(X—4Y)/(根号X—2倍根号Y)—(X+Y+2倍根号XY)/(X+根号XY)/(根号X/X+根号Y/Y)

=(√x-2√y)(√x+2√y)/(√x-2√y)-(√x+√y)²/[√x(√x+√y)]/(√x/x+√y/y)

=√x+2√y-(√x+√y)/[√x(√x+√y)/√(xy)]

=√x+2√y-√y

=√x+√y

代入x=1/2 y=8

原式=√2/2+2√2=5√2/2

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