Question

这个怎么算求详细的解题过程

Answer 1

y/√(4+y^2)=√5/5
5y=√5.√(4+y^2)
25y^2 =5(4+y^2)
20y^2 =20
y^2=1
y=1 or -1

Answer 2

y 应该大于 0.
两边平方，得
y^2 / (4 + y^2) = 1/5
5 y^2 = 4 + y^2
y^2 = 1
y = 1
y = - 1（舍去）

Answer 3

为简便, 设 X = 1000x, Y = 1000y, Z = 1000z 115X = 19000 + Y + 0.4Z .........(1) 12Y = 9000 + 5X + 0.6Z ..........(2) 6Z = 27000 + 10X + Y ............(3) (1)+(2): 110X + 11Y = 28000 + Z 11(10X + Y) = 28000 + Z .........(4)

Answer 4

y/√(4+y²)=√5/5
5y=√5√(4+y²)
25y²=5(4+y²)
20y²=20
y²=1
y1=1
y2=-1
经检验y=1是本方程的根。

Answer 5

y/√4+y^2=√5/5
√20+5y^2=5y
20+5y^2=25y^2
20y^2=20
y^2=1
y=±1，y＝-1是增根
∴原方程的根是y＝1