能做几个算几个1.2{3[4(5x-1)-8]-20}-7=1(解方程,列式子）2.1/2{1/3[1/4(1/5x-1)-6]+4=1(同上）3.x-2[x-3(x+4)-5]=3{2x-[x-8(x-4)]}-2(同上）

Question

能做几个算几个
1.2{3[4(5x-1)-8]-20}-7=1(解方程,列式子）
2.1/2{1/3[1/4(1/5x-1)-6]+4=1(同上）
3.x-2[x-3(x+4)-5]=3{2x-[x-8(x-4)]}-2(同上）

Answer 1

1.
2{3[4(5x-1-2)]-20}-7=1
2{12(5x-3)-20}-7=1
2{60x-56}-7=1
120x-112-7=1
x=1
2.
1/2{1/3[x/20-1/4-6]+4}=1
1/2{1/3[x/20-25/4]+4}=1
1/2{[x/60-25/12]+4}=1
1/2{[x/60+23/12}=1
x/120+23/24=1
x/120=1/24
x=5
3.
x-2[x-3x-12-5]=3{2x-[x-8x+32]}-2
x-2[-2x-17]=3{2x-[-7x+32]}-2
x+4x+34=3{2x+7x-32}-2
5x+34=3{9x-32}-2
5x+34=27x-96-2
132=22x
x=6