Bài 1 : tìm số nguyên x , biết :
1) x-8= -10
2) x-5= -(-7)
3) x-(-10) = -14
4) x + 47 = – (-16)
5) 16 + x =-(-15)
6)x+(-5)= – (-7)
7) 7-x=25
8)-18 – x = -23
9) -34-x= -(-45)
10)-x-15= -13
11) -x – (-5)= -12
12) -x +11= -23
13) |x| -10 = -(-8)
14) |x|+7=12 – (-3)
15) 3+|x|= -(-10)+|-4|
16)|x-5|-7=12
17)|2+x|+8=|-10|-2
18)-1+|7-x|=12-|-2|
Đáp án:
Giải thích các bước giải:
Điều kiện `x∈ZZ.`
`1) x-8=-10`
`<=> x= -10 + 8`
`<=>x =-2(tm)`
Vậy `x=-2.`
`2) x-5= -(-7)`
`<=>x – 5 = 7`
`<=> x= 7 + 5 `
`<=> x=12(tm).`
Vậy `x=12.`
`3) x-(-10) = -14`
`<=>x+10=-14`
`<=>x=-14-10`
`<=>x=-24(tm).`
Vậy `x=-24.`
`4) x + 47 = – (-16)`
`<=>x+47 = 16`
`<=>x=16-47`
`<=> x = -31(tm)`
Vậy `x=-31.`
`5)16 + x = -(-15)`
`<=> 16+x = 15`
`<=> x=15-16`
`<=>x=-1(tm).`
Vậy `x=-1.`
`6) x+(-5)= – (-7)`
`<=>x-5 = 7`
`<=> x= 7 + 5 `
`<=> x=12(tm).`
Vậy `x=12.`
`7) 7-x=25`
`<=> x = 7-25`
`<=>x=-18(tm).`
Vậy `x=-18.`
`8) -18 – x = -23`
`<=> 18 + x = 23`
`<=> x = 23 – 18`
`<=> x=5(tm).`
Vậy `x=5.`
`9) -34-x=-(-45)`
`<=> -(34+x)=-(-45)`
`<=>34+x = -45`
`<=> x = -45 -34`
`<=>x=-79(tm).`
Vậy `x=-79.`
`10) -x-15= -13`
`<=>x+15= 13`
`<=>x=13-15`
`<=>x=-2(tm).`
Vậy `x=-2.`
`11) -x – (-5)= -12`
`<=> -x + 5 = -12`
`<=>5-x=-12`
`<=> x= 5-(-12)`
`<=>x=17(tm).`
Vậy `x=17.`
`12)-x +11= -23`
`<=> -x = -23 – 11`
`<=>-x = -34`
`<=> x=34(tm).`
Vậy `x=34.`
`13)|x| -10 = -(-8)`
`<=>|x| -10 =8`
`<=> |x| = 8 + 10`
`<=> |x|=18`
`=>x=±18(tm)`
Vậy `x=±18.`
`14) |x|+7=12 – (-3)`
`<=> |x| = 12 + 3 – 7`
`<=> |x| = 8`
`=> x= ±8(tm).`
Vậy `x=±8.`
`15) 3+|x|= -(-10)+|-4|`
`<=> 3+|x|= 10+4`
`<=> |x| = 10+4-3`
`<=> |x| = 11`
`=>x=±11(tm)`
Vậy `x=±11.`
`16)|x-5|-7=12`
`<=> |x-5|=19`
`=>`\(\left[ \begin{array}{l}x-5=19\\x-5=-19\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=24(tm)\\x=-14(tm)\end{array} \right.\)
Vậy `x∈{-14; 24}.`
`17)|2+x|+8=|-10|-2`
`<=> |2+x|=10 – 2 – 8 =0`
`=> 2+x=0`
`=>x=-2`
Vậy `x=-2.`
`18) -1+|7-x|=12-|-2|`
`<=>|7-x| = 12 – 2 + 1`
`<=>|7-x| = 11`
`=>`\(\left[ \begin{array}{l}7-x=11\\7-x=-11\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=-4(tm)\\x=18(tm)\end{array} \right.\)
Vậy `x∈{-4;18}.`
1)x=-2
2)x=12
3)x=-24
4)x=-31
5)x=-1
6)x=12
7)x=-18
8)x=5
9)x=-79
10)x=-2
11)17
12)34
13)18
14)8
15)11
16)0
17)-2
18)4