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a) (125 - x) + 25 = 98
125 - x = 98 - 25
125 - x = 73
x = 125 - 73
x = 52
b) 100 : (x + 20) = 68 : 34
100 : (x + 20) = 2
x + 20 = 100 : 2
x + 20 = 50
x = 50 - 20
x = 30
c) (3x + 12) . 5 = 25 . 4 - 10
(3x + 12) . 5 = 100 - 10
(3x + 12) . 5 = 90
3x + 12 = 90 : 5
3x + 12 = 18
3x = 18 - 12
3x = 6
x = 6 : 2
x = 3
d) 210 : (2x - 3) - 20 = 10
210 : (2x - 3) = 10 + 20
210 : (2x - 3) = 30
2x - 3 = 210 : 30
2x - 3 = 70
2x = 70 + 3
2x = 73
x = 73/2
a, ( 125 - x ) + 25 = 98
⇒ 125 - x = 73
⇒ x = 52.
Vậy..
b, 100 : ( x + 20 ) = 68 : 34
⇒ 100 : ( x + 20 ) = 2
⇒ x + 20 = 50
⇒ x = 30
Vậy...
c, ( 3 . x + 12 ) . 5 = 25 . 4 - 10
⇒ ( 3 . x + 12 ) . 5 = 90
⇒ 3 .x + 12 = 18
⇒ 3x = 6
⇒ x = 2.
Vậy...
d, 210 : ( 2 .x - 3 ) - 20 = 10
⇒ ( 2 .x - 3 ) - 20 = 21
⇒ 2x - 3 = 41
⇒ 2x = 44
⇒ x = 22.
Vậy..
a) \(15\cdot5+75\cdot5+5\cdot3+5\cdot7\)
\(=5\left(15+75\right)+5\left(3+7\right)\)
\(=5\cdot90+5\cdot10=5\left(90+10\right)=5\cdot100=500\)
b) \(2\cdot200+4\cdot200+4\cdot50+125\cdot8\)
\(=2.2.100+4\cdot200+4\cdot50+125\cdot2\cdot4\)
\(=4\left(100+200+50+250\right)\)
\(=4\cdot600=2400\)
c) \(125\cdot20\cdot80\cdot2\cdot100\cdot5\)
\(=\left(125\cdot8\right)\cdot\left(2\cdot5\right)\cdot100\cdot20\)
\(=1000\cdot10\cdot100\cdot20\)
\(=20000000\)
a) \(18+25\times4-4^3\)
\(=18+100-64\)
\(=118-64\)
\(=54\)
b) \(275-\left(49+125\div5^3\right)\)
\(=275-\left(49+125\div125\right)\)
\(=275-\left(49+1\right)\)
\(=275-49-1\)
\(=226-1\)
\(=225\)
c) \(2015+\left(8\times15-\left(18-8\right)^2\right)\)
\(=2015+\left(8\times15-\left(10\right)^2\right)\)
\(=2015+\left(8\times15-100\right)\)
\(=2015+\left(120-100\right)\)
\(=2015+20\)
\(=2035\)
\(\frac{\frac{125}{8}+\frac{125}{97}+\frac{125}{576}+\frac{250}{991}}{\frac{25}{8}+\frac{25}{97}+\frac{25}{576}+\frac{50}{991}}\)=\(\frac{250.\left(\frac{1}{8}+\frac{1}{97}+\frac{1}{576}+\frac{1}{991}\right)}{50.\left(\frac{1}{8}+\frac{1}{97}+\frac{1}{576}+\frac{1}{991}\right)}\)=\(\frac{250}{50}\)=5
Trả lời
a) 9 . 24 . 25 = 9 . 600 = 5400
b) 12 . 125 . 54 = 1500 . 54 = 81000
c) 64 . 125 . 875 = 8000 . 875 = 7000000
d) 425 . 7 . 4 - 170 . 60 = 11900 - 10200 = 1700
e) 8 . 9 . 14 . 6 . 17 . 12 . 19 . 4 . 18 =
\(a,400:25=16\)
\(b,864:125=6,912\)
\(c,165:15=11\)
\(d,143:13=11\)
Bài 1 : Tính nhanh
a) 212 + 109 + 188
= (212 +188 ) + 109
= 400 + 109
= 509
b, 305 + 295 + 140
= ( 305 + 295 ) +140
= 600 + 140
= 740
c, 9 . 4 . 25 . 8 . 125
= ( 8. 125 ) ( 4 .25 ) 9
= 1000 . 100 . 9
= 900000
d, 35 + 56 + 65 + 44
= (35 + 65) + ( 56 + 44)
= 100 + 100
= 200
e, 277 + 194 + 206 + 123
= ( 277 +123 ) + (194 + 206)
= 400 + 400
= 800
g, 8 . 25 . 2 . 4 . 5 . 125
= ( 8.125 ) . ( 25.4 ) . (2.5)
= 1000.100.10
= 1000000
h, 29 . 25 + 29 . 45 + 29 . 30
= 29 ( 25+45+30)
= 29 .100
= 2900
i, 36 . ( 143 + 57 ) + 64 . ( 143 + 57 )
= 36 . 200 + 64 . 200
= 200 ( 36 + 64 )
= 200 . 100
= 20000
k, 491 . ( 747 + 53 ) + 491 . ( 153 + 47)
= 491 . 800 + 491 . 200
= 491 ( 800 +200 )
= 491 .1000
= 491000
~~~Chúc bn học tốt~~~
Bài 4 :
a) M = 1 + 2 + 3 +... + 103
Số số hạng là : (103 - 1 ) : 1 + 1 = 103
Tổng : ( 1 + 103 ) . 103 : 2 = 5356
b, N = 3 + 7 + 11 +...+ 99
Số số hạng là : ( 99 - 3 ) : 4 +1 = 25
Tổng : ( 3 + 99 ) . 25 : 2 = 1275
c) C = 1+ 11 + 21 + ... + 991
Số số hạng : ( 991 -1 ) : 10 +1 = 100
Tổng : ( 1 + 991 ) . 100 : 2 = 49600
~~~ Chúc bn hc tốt ~~~
a) 9 x 24 x 25
=216x25
=5400
b) 12 x 125 x 54
=1500x54
=81000
c) 64 x 125 x 875
=8000x875
=7000000
d) 425 x 7
a) 9 x 24 x 25
b) 12 x 125 x 54
c) 64 x 125 x 875
d) 425 x 7 x4 - 170 x 60
=2975x4 - 170 x 60
=11900- 170 x 60
=11900-10200
=1700
e) 8 x 9 x 14 + 6 x 7 x 12 + 19 x 4 x 18
=1008+504+1368
=2880
a) 125 . 10 = 1 250
b) 2 021 . 100 = 202 100
c) 1 991 . 25 . 4 = 1 991 . (25 . 4) = 1 991 . 100 = 199 100
d) 3 025 . 125 . 8 = 3 025 . (125 . 8)
= 3 025 . 1 000 = 3 025 000