1.
-3^2-[-9÷（-3）^2-1]-(-5)^2×（-2）^3÷1/0.25
=-9 -[ -9÷9 -1] - 25×（-8）÷4
=-9+2 +50
=43
2.
1-(7+3x)/8=(3x-10)/(4-x)
(1-3x)/8=(3x-10)/(4-x)
3x^-13x+4=24x-80
3x^-37x+84=0
(3x-28)(x-3)=0
x=28/3 x=3
3.
20%x+(1-20%)(320-x)=320×40%
x +4*(320-x)=640
640 =3x
x=640/3
4.
已知(m^2-1)x^2-(m+1)x+8=0是关于X的一元一次方程
m^-1=0 m=1,或者m=-1
m+1不等于0,所以 m=1
-2x+8=0 x=4
199(1+2)(4-2)+3+4
=1201