Bài 1: Thực hiện các phép tính sau
1, 12-(13+7)+(-9)
2,47-(90-13+47)-13
3,-(145-79)+(245-79)
4,-13-|-34|-7+98
5,|-87|+(-17)-(14-80)
6, (-17-30)+28-(-5)
7, 12-(-7+40)+37
8, (23-45+87)-(97+23)
9,13-(-67)+35-6
10, (-76+23)-(-45+33)
11, (160-200)-(560-|-235+35|)
12, 45:|-6-3|+(-15)-(-7)-34
13, -56-(-45)+13-45-(-56)
Bài 2: Tìm x:
1, x-13=34
2, 3-x=15
3, 23+(x-5)=-7
4, 2(x-5)=-18+40
5, -12+30=x-4
6, -x+23=-6-7
7, 2-(x-1)=|-3|+7
8, -3+56-8=7+x
9, 9-(13-x)=-6
10, -x+34=9-37
Bài 1:
1, 12 – (13 + 7) + (-9)
\(= 12 – 20 – 9\)
\(= -17\)
2, 47 – (90 – 13 + 47) – 13
\(= 47 – 90 + 13 – 47 – 13\)
\(= -90\)
3, -(145 – 79) + (245 – 79)
\(= -66 + 245 – 79\)
\(= 100\)
4, -13 – |-34| – 7 + 98
\(= -13 – 34 – 7 + 98\)
\(= 44\)
5, |-87| + (-17) – (14 – 80)
\(= 87 – 17 + 66\)
\(= 136\)
6, (-17 – 30) + 28 – (-5)
\(= -47 + 28 + 5\)
\(= -14\)
7, 12 – (-7 + 40) + 37
\(= 12 – 33 + 37\)
\(= 16\)
8, (23 – 45 + 87) – (97 + 23)
\(= 65 – 120\)
\(= -55\)
9, 13 – (-67) + 35 – 6
\(= 13 + 67 + 35 – 6\)
\(= 109\)
10, (-76 + 23) – (-45 + 33)
\(= -53 + 12\)
\(= -41\)
11, (160 – 200) – (560 – |-235 + 35|)
\(= -40 – (560 – 200)\)
\(= -40 – 360\)
\(= -400\)
12, 45 : |-6 – 3| + (-15) – (-7) – 34
\(= 45 : 9 – 15 + 7 – 34\)
\(= 5 – 15 + 7 – 34\)
\(= -37\)
13, -56 – (-45) + 13 – 45 – (-56)
\(= -56 + 45 + 13 – 45 + 56\)
\(= 13\)
Bài 2:
1, x – 13 = 34
\(⇒ x = 34 + 13\)
\(⇒ x = 47\)
2, 3 – x = 15
\(⇒ x = 3 – 15\)
\(⇒ x = -12\)
3, 23 + (x – 5) = -7
\(⇒ x – 5 = -7 – 23\)
\(⇒ x – 5 = -30\)
\(⇒ x = -30 + 5\)
\(⇒ x = -25\)
4, 2(x – 5) = -18 + 40
\(⇒ 2x – 10 = 22\)
\(⇒ 2x = 22 + 10\)
\(⇒ 2x = 32\)
\(⇒ x = 16\)
5, -12 + 30 = x – 4
\(⇒ x – 4 = 18\)
\(⇒ x = 18 + 4\)
\(⇒ x = 22\)
6, -x + 23 = -6 – 7
\(⇒ -x = -13 – 23\)
\(⇒ -x = -36\)
\(⇒ x = 36\)
7, 2 – (x – 1) = |-3| + 7
\(⇒ 2 – (x – 1) = 10\)
\(⇒ x – 1 = 2 – 10\)
\(⇒ x = -8 + 1\)
\(⇒ x = -7\)
8, -3 + 56 – 8 = 7 + x
\(⇒ 7 + x = 45\)
\(⇒ x = 45 – 7\)
\(⇒ x = 38\)
9, 9 – (13 – x) = -6
\(⇒ 13 – x = 9 + 6\)
\(⇒ x = 13 – 15\)
\(⇒ x = -2\)
10, -x + 34 = 9 – 37
\(⇒ -x = -28 – 34\)
\(⇒ -x = -62\)
\(⇒ x = 62\)
Đáp án:
Giải thích các bước giải:
Bài 1 :
`1,12-(13+7)+(-9)`
`=12-20-9`
`=-17`
,
`2,47-(90-13+47)-13`
`=47-90+13-47-13`
`=-90`
,
`3,-(145-79)+(245-79)`
`=-145+79+245-79`
`=-145+245`
`=100`
,
`4,-13-|-34|-7+98`
`=-13-34-7+89`
`=35`
,
`5,|-87|+(-17)-(14-80)`
`=87-17-14+80`
`=136`
,
`6,(-17-30)+28-(-5)`
`=-17-30+28+5`
`=-14`
,
`7,12-(-7+40)+37`
`=12+7-40+37`
`=16`
,
`8,(23-45+87)-(97+23)`
`=23-45+87-97+23`
`=-55`
,
`9,13-(-67)+35-6`
`=13+67+35-6`
`=109`
,
`10,(-76+23)-(-45+33)`
`=-76+23+45-33`
`=-41`
,
`11,(160-200)-(560-|235+35|)`
`=-40-560+|200|`
`=-600+200`
`=-400`
.
`12,45:|-6-3|+(-15)-(-7)-34`
`=45:|-9|-15+7-34`
`=45:9-42`
`=5-42`
`=-37`
,
`13,-56-(-45)+13-45-(-56)`
`=56+45+13-45+56`
`=13`
Bài 2 :
`1,x-13=34`
`\to x=34+13`
`\to x=47`
Vậy `x=47`
,
`2,3-x=15`
`\to -x=15-3`
`\to -x=12`
`\to x=-12`
Vậy `x=-12`
.
`3,23+(x-5)=-7`
`\to 23+x-5=-7`
`\to 18+x=-7`
`\to x=-7-18`
`\to x=-25`
Vậy `x=-25`
,
`4,2(x-5)=-18+40`
`\to 2x-10=22`
`\to 2x=22+10`
`\to 2x=32`
`\to x=32:2`
`\to x=16`
Vậy `x=16`
,
`5,-12+30=x-4`
`\to 18=x-4`
`\to x=18+4`
`\to x=22`
Vậy `x=22`
,
`6,-x+23=-6-7`
`\to -x+23=-13`
`\to -x=-13-23`
`\to -x=-36`
`\to x=36`
Vậy `x=36`
,
`7,2-(x-1)=|-3|+7`
`\to 2-x+1=3+7`
`\to 3-x=10`
`\to -x=10-3`
`\to -x=7`
`\to x=-7`
Vậy `x=-7`
,
`8,-3+56-8=7+x`
`\to 45=7+x`
`\to x=45-7`
`\to x=38`
Vậy `x=38`
,
`9,9-(13-x)=-6`
`\to 9-13+x=-6`
`\to -4+x=-6`
`\to x=-6+4`
`\to x=-2`
Vậy `x=-2`
,
`10,-x+34=9-37`
`\to -x+34=-28`
`\to -x=-28-34`
`\to -x=-62`
`\to x=62`
Vậy `x=62`