解:解方程, 此方程的解为x = 3
7.8(6 + x) = 70.2
7.8 × 6 + 7.8 × x = (70×10+2)/10
(7×10+8)/10 × 6 + [(7×10+8)/10]x = 702/10
78/10 × 6+ (78/10)x = 702/10
468/10 + (39/5)x = 702/10
(39/5)x = 702/10 - 468/10
(39/5)x = 234/10
(39/5)x = 117/5
x = 117/5 ÷ 39/5
x = 117/5 × 5/39
∴x = 3
答:此方程的解为x = 3
先算乘除 去括号,剩加减后,移项运算即可
这里有括号,括号里的看作一个整体,相当于是乘法
6+ x=70.2÷7.8=9
x=9-6=3
7.8(6+x)=70.2
解:去括号,得
46.8+7.8x=70.2
方程两边都减去46.8,得
46.8-46.8+7.8x=70.2-46.8
7.8x=23.4
系数化为,得
x=3
解:46.8+7.8x=70.2(左式利用乘法分配律)
7.8x=23.4(等式两边同时减去46.8)
x=3(等式两边同时除以7.8)
解:46.8+7.8x=70.2
7.8x=23.4
x=3