【1】
m≥0
x = 2m^(1/2) >= 0,
x = -3|n| <= 0.
0 <= x <= 0
x = 0.
m = (x/2)^2 = 0
|n| = x/(-1) = 0,
n = 0.
则
3m^(1/2) + 5|n| = 0.
但这与3m^(1/2) + 5|n| = 7矛盾.
所以,x无解.
如果题目是,
若m.n(m≥0)满足3√m+5|n|=7,x=2√m=3|n|,求x的求值范围
这样的话,
x = 2√m = 3|n|,
√m = x/2,
|n| = x/3
7 = 3m^(1/2) + 5|n| = 3（x/2） + 5(x/3) = x(3/2 + 5/3) = x(19/6)
x = 6*7/19 = 42/19
【2】不会
【3】
设x=√a-b, y=√c, z=*
则x>=0,y>=03x+4y=16 3x<=16 x<=16/3
4y<=16 y<=4
z=4x-3y<=4*16/3=64/3z=4x-3y>=-3*4=-12
*的取值范围 -12<=*<=64/3
【4】不会
【5】不会
【6】不会
【7】根号13的整数部分是3 小数部分是根号13-3
M+N=根号13
M-N等于3-（根号13-3）=-根号3
所以结果嘚-1
应该对吧..好难啊