解方程
5x+7=42
x÷4.2=2
3.6x-x=3.25
2(x-3)=5.8.
(1)5x+7=42,
5x+7-7=42-7,
5x=35,
x=7;
(2)x÷4.2=2,
x÷4.2×4.2=2×4.2,
x=8.4;
(3)3.6x-x=3.25,
(3.6-1)x=3.25,
2.6x=3.25,
2.6x÷2.6=3.25÷2.6,
x=1.25;
(4)2(x-3)=5.8,
x-3=2.9,
x-3+3=2.9+3,
x=5.9.
解方程
5x+7=42
x÷4.2=2
3.6x-x=3.25
2(x-3)=5.8.
(1)5x+7=42,
5x+7-7=42-7,
5x=35,
x=7;
(2)x÷4.2=2,
x÷4.2×4.2=2×4.2,
x=8.4;
(3)3.6x-x=3.25,
(3.6-1)x=3.25,
2.6x=3.25,
2.6x÷2.6=3.25÷2.6,
x=1.25;
(4)2(x-3)=5.8,
x-3=2.9,
x-3+3=2.9+3,
x=5.9.