* 1999 – 2000 + 2999 – 3000 + 3999 – 4000 + 4999 – 5000 + 5999 – 1000
T×m X
* X x 5 + 122 + 236 = 633
* 320 + 3 x X = 620
* 357 : X = 5 d 7
* X : 4 = 1234 d 3
* 120 – ( X x 3 ) = 30 x 3
* 357 : ( X + 5 ) = 5 d 7
* 65 : x = 21 d 2
* 64 : X = 9 d 1
* ( X + 3) : 6 = 5 + 2
* X x 8 – 22 = 13 x 2
* 720 : ( X x 2 + X x 3 ) = 2 x 3
* X+ 13 + 6 x X = 62
* 7 x ( X – 11 ) – 6 = 757
* X + ( X + 5 ) x 3 = 75
* 4 < X x 2 < 10
* 36 > X x 4 > 4 x 1
* X + 27 + 7 x X = 187
* X + 18 + 8 x X = 99
* ( 7 + X ) x 4 + X = 108
* ( X + 15 ) : 3 = 3 x 8
* ( X : 12 ) x 7 + 8 = 36
* X : 4 x 7 = 252
* ( 1+ x) +( 2 + x) + ( 3 + x) + ( 4 + x ) + ( 5 + x) = 10 x 5
* ( 8 x 18 – 5 x 18 – 18 x 3 ) x X + 2 x X = 8 x 7 + 24
* 1999 – 2000 + 2999 – 3000 + 3999 – 4000 + 4999 – 5000 + 5999 – 1000 T×m X * X x 5 + 122 + 236 = 633
By Gabriella
Bài 1:
`1999-2000+2999-3000+3999-4000+4999-5000+5999-1000`
`=(1999-1000)+(2999-2000)+(3999-3000)+(4999-4000)+(5999-5000)`
`=999+999+999+999+999+999`
`=999×5`
`=4995`
Bài 2:
`1)x×5+122+236=633`
`x×5+358=633`
`x×5=633-358`
`x×5=275`
`x=275:5`
`x=55`
`2)320+3×x=620`
`3×x=620-320`
`3×x=300`
`x=300:3`
`x=100`
`3)357:x=5(dư` `7)`
`x=(357-7):5`
`x=350:5`
`x=70`
`4)x:4=1234(dư` `3)`
`x=(1234×4)+3`
`x=4936+3`
`x=4939`
`5)120-(x×3)=30×3`
`120-(x×3)=90`
`x×3=120-90`
`x×3=30`
`x=30:3`
`x=10`
`6)357:(x+5)=5(dư` `7)`
`x+5=(357-7):5`
`x+5=350:5`
`x+5=70`
`x=70-5`
`x=65`
`7)65:x=21(dư` `2)`
`x=(65-2):21`
`x=63:21`
`x=3`
`8)64:x=9(dư` `1)`
`x=(64-1):9`
`x=63:9`
`x=7`
`9)(x+3):6=5+2`
`(x+3):6=7`
`x+3=7×6`
`x+3=42`
`x=42-3`
`x=39`
`10)x×8-22=13×2`
`x×8-22=26`
`x×8=26+22`
`x×8=48`
`x=48:8`
`x=6`
`11)720:(x×2+x×3)=2×3`
`720:(x×2+x×3)=6`
`x×2+x×3=720:6`
`x×2+x×3=120`
`x×(2+3)=120`
`x×5=120`
`x=120:5`
`x=24`
`12)x+13+6×x=62`
`x+6×x+13=62`
`x+6×x=62-13`
`x+6×x=49`
`x×(1+6)=49`
`x×7=49`
`x=49:7`
`x=7`
`13)7×(x-11)-6=757`
`7×(x-11)=757+6`
`7×(x-11)=763`
`x-11=763:7`
`x-11=109`
`x=109+11`
`x=120`
`14)x+(x+5)×3=75`
`x+3×x+3×5=75`
`x+3×x+15=75`
`4×x+15=75`
`4×x=75-15`
`4×x=60`
`x=60:4`
`x=15`
`15)4<x×2<10`
`⇔4/2<(x×2)/2<10/2`
`⇔2<x<5`
`⇒x∈{3;4}`
`16)36>x×4>4×1`
`⇔36/4>(x×4)/4>(4×1)/4`
`⇔9>x>1`
`⇒x∈{8;7;6;5;4;3;2}`
`17)x+27+7×x=187`
`(x+7×x)+27=187`
`x×(1+7)+27=187`
`x×8+27=187`
`x×8=187-27`
`x×8=160`
`x=160:8`
`x=20`
`18)x+18+8×x=99`
`(x+8×x)+18=99`
`x×(1+8)+18=99`
`x×9+18=99`
`x×9=99-18`
`x×9=81`
`x=81:9`
`x=9`
`19)(7+x)×4+x=108`
`4×7+4×x+x=108`
`28+5×x=108`
`5×x=108-28`
`5×x=80`
`x=80:5`
`x=16`
`20)(x+15):3=3×8`
`(x+15):3=24`
`x+15=24×3`
`x+15=72`
`x=72-15`
`x=57`
`21)(x:12)×7+8=36`
`(x:12)×7=36-8`
`(x:12)×7=28`
`x:12=28:7`
`x:12=4`
`x=4×12`
`x=48`
`22)x:4×7=252`
`x:4=252:7`
`x:4=36`
`x=36×4`
`x=144`
`23)(1+x)+(2+x)+(3+x)+(4+x)+(5+x)=10×5`
`1+x+2+x+3+x+4+x+5+x=50`
`(1+2+3+4+5)+(x+x+x+x+x)=50`
`15+5×x=50`
`5×x=50-15`
`5×x=35`
`x=35:5`
`x=7`
`24)(8×18-5×18-18×3)×x+2×x=8×7+24`
`[18×(8-5-3)]×x+2×x=56+24`
`(18×0)×x+2×x=80`
`0×x+2×x=80`
`2×x=80`
`x=80:2`
`x=40`
T×m X
* X x 5 + 122 + 236 = 633
X =275 :5
x=55
* 320 + 3 x X = 620
x=300:3
x=100
* 357 : X = 5 d 7
X=(357-7):5
x = 70
* X : 4 = 1234 d 3
x= (1234:4) +3
x=4939
* 120 – ( X x 3 ) = 30 x 3
x=30:3
x=10
* 357 : ( X + 5 ) = 5 d 7
x=65
* 65 : x = 21 d 2
x= 3
* 64 : X = 9 d 1
x=7
* ( X + 3) : 6 = 5 + 2
x=39
* X x 8 – 22 = 13 x 2
x=6
* 720 : ( X x 2 + X x 3 ) = 2 x 3
x=24
* X+ 13 + 6 x X = 62
x=
* 7 x ( X – 11 ) – 6 = 757
x=
* X + ( X + 5 ) x 3 = 75
x= 9
4
* X + 27 + 7 x X = 187
x=16
* X + 18 + 8 x X = 99
x=57
* ( 7 + X ) x 4 + X = 108
x=48
* ( X + 15 ) : 3 = 3 x 8
x=144
* ( X : 12 ) x 7 + 8 = 36
x=7
* X : 4 x 7 = 252
x = 252 : 28
x=144
* ( 1+ x) +( 2 + x) + ( 3 + x) + ( 4 + x ) + ( 5 + x) = 10 x 5
X=7
* ( 8 x 18 – 5 x 18 – 18 x 3 ) x X + 2 x X = 8 x 7 + 24
x=40
do thêm cái này
* 1999 – 2000 + 2999 – 3000 + 3999 – 4000 + 4999 – 5000 + 5999 – 1000
=999×4 +1999-1000
=4995
mình lười quá nên tính máy tính