4 200:21+16 800:21
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) 2 x 6 = 12 3 x 7 = 21
12 : 2 = 6 21 : 3 = 7
12 : 6 = 2 21 : 7 = 3
4 x 8 = 32 5 x 9 = 45
32 : 4 = 8 45 : 5 = 9
32 : 8 = 4 45 : 9 = 5
b) 600 : 3 = 200 800 : 4 = 200 400 : 2 = 200
600 : 2 = 300 800 : 2 = 400 500 : 5 = 100
a) 2x6=12 3x7=21
12:2=6 21:3=7
12:6=2 21:7=3
4x8=32 5x9=45
32:4=8 45:5=9
32:8=4 45:9=5
b) 600:3=200 800:4=200 400:2=200
600:2=300 800:2=400 500:5=100
A Legend Never Dies
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a) x-15+124=200
x-15=200-124
x-15=76
x=76+15
x=91
Vậy x=91.
b) 3x-21=36:34
3x-21=32
3x-21=9
3x=9+21
3x=30
x=30:3
x=10
Vậy x=10.
c) x-48:16=21
x-3=21
x=21+3
x=24
Vậy x=24.
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\(21+21+21+...+21+21+16+16+16+...+16.\) (84 số 21 và 21 số 16)
\(=84\cdot21+21\cdot16=21\left(84+16\right)=21\cdot100=2100\)
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\(\left(\frac{27}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+\frac{1}{2}\)
\(=1+1+\frac{1}{2}\)
\(=\frac{5}{2}\)
k cho mk nha!
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a: =197+3*(34-64)
=197-3*30
=197-90=107
b: =25(134-34)+100=100*26=2600
d: =>x thuộc B(84)
mà 100<x<200
nên x=168
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(- 4) . (+21) . (- 25) . (- 2)
= (-4).(-25).(+21).(-2)
= 100.(+21).(-2)
= -4200
Đáp án: C
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\(a,1-2+3-4+5-6+......+199-200\)
\(=\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+.....+\left(199-200\right)\)( 100 cặp )
\(=-1+\left(-1\right)+\left(-1\right)+........+\left(-1\right)\)( 100 số hạng )
\(=-1.100\)
\(=-100\)
\(a.1-2+3-4+5-6+...+199-200\)
\(=\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+...+\left(199-200\right)\) (có tất cả \(200:2=100\)cặp)
\(=\left(-1\right)+\left(-1\right)+\left(-1\right)+...+\left(-1\right)\)
\(=\left(-1\right).200=-200\)
\(b.1+2-3-4+5+6-7-8+...+97+98-99-100\)
\(=\left(1+2-3-4\right)+\left(5+6-7-8\right)+...+\left(97+98-99-100\right)\) (có \(100:4=25\)cặp)
\(=\left(-4\right)+\left(-4\right)+...+\left(-4\right)\)
\(=\left(-4\right).25=-100\)
\(c.1+\left(-6\right)+11+\left(-16\right)+...+21+\left(-26\right)\)
\(=\left[1+\left(-6\right)\right]+\left[11+\left(-16\right)\right]+...+\left[21+\left(-26\right)\right]\) (có tất cả \(26:2=13\)cặp)
\(=\left(-5\right)+\left(-5\right)+...+\left(-5\right)\)
\(=-5.13=-65\)
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\(1\dfrac{4}{23}+\left(\dfrac{5}{21}-\dfrac{4}{23}\right)+\dfrac{16}{21}-\dfrac{1}{2}\)
\(=1\dfrac{4}{23}-\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{16}{21}+\dfrac{1}{2}\)
\(=1+1-\dfrac{1}{2}\)
\(=\dfrac{3}{2}\)
1 4/23 + ( 5/21-4/23 ) + 16/21 - 1/2
=1 4/23 - 4/23 + 5/21 + 16/21 + 1/2
= 1+1-1/2
=3/2
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\(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\)
= \(\left(1\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)-0,5\)
= 1+1-0,5
=1,5
4200:21+16800:21
=(4200+16800):21
=21000:21
=1000
1 jack