一、在$◯$里填运算符号,在$□$里填数。
1. $x - 42 = 58$
$x - 42 + 42 = 58◯
2. $x + 17 = 57$
$x + 17 - 17 = 57◯
3. $x ÷ 7 = 105$
$x ÷ 7 × 7 = 105◯
4. $0.9x = 6.3$
$0.9x ÷ 0.9 = 6.3◯
5. $x + 25 = 70$
$x + 25 - 25 = 70◯
6. $3x - 15 = 45$
$3x - 15 + 15 = 45◯
1. $x - 42 = 58$
$x - 42 + 42 = 58◯
+
□42
$ $x = □100
$2. $x + 17 = 57$
$x + 17 - 17 = 57◯
-
□17
$ $x = □40
$3. $x ÷ 7 = 105$
$x ÷ 7 × 7 = 105◯
×
□7
$ $x = □735
$4. $0.9x = 6.3$
$0.9x ÷ 0.9 = 6.3◯
÷
□0.9
$ $x = □7
$5. $x + 25 = 70$
$x + 25 - 25 = 70◯
-
□25
$ $x = □45
$6. $3x - 15 = 45$
$3x - 15 + 15 = 45◯
+
□15
$ $x = □20
$
答案:
1.+,42,100 2.-,17,40 3.×,7,735 4.÷,0.9,7 5.-,25,45 6.+,15,20
二、括号中哪个$x$的值是方程的解,请把它圈出来。
1. $85 - x = 27(x = 58$ $x = 62$ $x = 112)$
2. $x + 7.9 = 15.2(x = 6.5$ $x = 7.3$ $x = 23.1)$
3. $12x = 4.8(x = 0.4$ $x = 4$ $x = 57.6)$
4. $x - 1.9 = 1.9(x = 0$ $x = 3.8$ $x = 4.2)$
5. $x + 4.5 = 10(x = 5.5$ $x = 6.5$ $x = 14.5)$
6. $3(x - 2) = 15(x = 3$ $x = 5$ $x = 7)$
1. $85 - x = 27(x = 58$ $x = 62$ $x = 112)$
2. $x + 7.9 = 15.2(x = 6.5$ $x = 7.3$ $x = 23.1)$
3. $12x = 4.8(x = 0.4$ $x = 4$ $x = 57.6)$
4. $x - 1.9 = 1.9(x = 0$ $x = 3.8$ $x = 4.2)$
5. $x + 4.5 = 10(x = 5.5$ $x = 6.5$ $x = 14.5)$
6. $3(x - 2) = 15(x = 3$ $x = 5$ $x = 7)$
答案:
1.x=58 2.x=7.3 3.x=0.4 4.x=3.8 5.x=5.5 6.x=7
三、解方程(带※号的要验算)。
$x + 1.6 = 3.5$ $6x = 13.2$
$2.5x = 8$ ※$x + 17.5 = 60$
※$4x = 3.6$ ※$x ÷ 3.5 = 2$
$x - 2.5 = 7.5$ $4(x + 3) = 32$
$2.5x - 1.5 = 8.5$
$x + 1.6 = 3.5$ $6x = 13.2$
$2.5x = 8$ ※$x + 17.5 = 60$
※$4x = 3.6$ ※$x ÷ 3.5 = 2$
$x - 2.5 = 7.5$ $4(x + 3) = 32$
$2.5x - 1.5 = 8.5$
答案:
x=1.9,x=2.2,x=3.2,x=42.5,x=0.9,x=7,x=10,x=5,x=4(验算略)
四、看图列方程,并求出方程的解。
1.

2.


1.
2.
答案:
1.x+3.5=20,x=16.5 2.4y=200,y=50 3.5z=75,z=15 4.2x+30=150,x=60 5.x+3×5=2x,x=15
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