..已知,(y-z)²-4(z-y)(x-y)=0,求证:x+z=-y已知:a²+b²+2c²+2bc-2ac=0,求a+b的值

Question

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已知,(y-z)²-4(z-y)(x-y)=0,求证:x+z=-y
已知:a²+b²+2c²+2bc-2ac=0,求a+b的值

Answer 1

已知,(y-z)²-4(z-y)(x-y)=0,求证:x+z=-y
题目不对,取x=z=1,y=-2
(y-z)²-4(z-y)(x-y)=3^2-4*3*3=-27
原式=(3y+z-4x)(z-y)=0
所以3y+z=4x或z=y
已知:a²+b²+2c²+2bc-2ac=0,求a+b的值
配方:
(a-c)^2+(b+c)^2=0
所以a-c=0
b+c=0
a+b=0