Tìm x, biết
6/7-x=2/3
1
4/4
32/21
4/21
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18: Chiều rộng là 150*1/3=50dm=5m
Chiều dài là 150dm=15m
Diện tích mảnh đất là:
15*5=75m2
`-214-[(117-x)-314]=0`
`=> -214-(117-x-314)=0`
`=> -214-117+x+314=0`
`=> x-17=0`
`=> x=0+17`
`=> x=17`
\(-214-[\left(117-x\right)-314]\text{=}0\)
\(-214-\left(117-x-314\right)\text{=}0\)
\(-214-117+x+314\text{=}0\)
\(x-17\text{=}0\)
\(x\text{=}17\)
\(6\cdot x+9=15\)
\(\Rightarrow6\cdot x=15-9\)
\(\Rightarrow6\cdot x=6\)
\(\Rightarrow x=\dfrac{6}{6}=1\)
_______________
\(43+2x=49\)
\(\Rightarrow2x=49-43\)
\(\Rightarrow2x=6\)
\(\Rightarrow x=\dfrac{6}{2}=3\)
____________
\(x:2+5=11\)
\(\Rightarrow x:2=11-5\)
\(\Rightarrow x:2=6\)
\(\Rightarrow x=6\cdot2=12\)
______________
\(77-11x=0\)
\(\Rightarrow11x=77\)
\(\Rightarrow x=\dfrac{77}{11}\)
\(\Rightarrow x=7\)
_______________
\(12-4:x=8\)
\(\Rightarrow4:x=12-8\)
\(\Rightarrow4:x=4\)
\(\Rightarrow x=\dfrac{4}{4}=1\)
_____________
\(x:3+8=11\)
\(\Rightarrow x:3=11-8\)
\(\Rightarrow x:3=3\)
\(\Rightarrow x=3\cdot3=9\)
a: 6x+9=15
=>6x=6
=>x=1
b: 2x+43=49
=>2x=6
=>x=3
c: x:2+5=11
=>x:2=6
=>x=12
d: 77-11x=0
=>7-x=0
=>x=7
e: 12-4:x=8
=>4:x=4
=>x=1
f: x:3+8=11
=>x:3=3
=>x=9
257 x 432 + 257 x 354 + 257 x 214
= 257 x ( 432 + 354 + 214 )
= 257 x 1000
= 257000
Đáp án cần chọn là: B
Vì 318⋮2;210⋮2;104⋮2;432⋮2 nên A=(318+210+104+432)⋮2.
Ta cóM=214+19+21=214+40
Vì 214⋮2;40⋮2 nên M=(214+19+21)⋮2.
Vì 112⋮2;328⋮2;516⋮2;467 không chia hết cho 2 nên B=(112+467+328+516) không chia hết cho 2.
Vậy có A và M chia hết cho 2.
Bài 2:
a) 37 x 7 - 17 x 11 + 13 x 37 + 17 x 21
b) 55 x 52 : 54 - 28 : 24
c) 311 x 12 + 312 x 5 - 314
`#040911`
`a)`
\(37 \times 7 - 17 \times 11 + 13 \times 37 + 17 \times 21\)
`= 37 \times (7 + 13) + 17 \times (21 - 11)`
`= 37 \times 20 + 17 \times 10`
`= 10 \times (37 \times 2 + 17)`
`= 10 \times 91`
`= 910`
`b)`
\(5^5 \times 5^2 \div 5^4 - 2^8 \div 2^4\)
`=`\(5^{5+2-4}-2^{8-4}\)
`= 5^3 - 2^4`
`= 125 - 16`
`= 109`
`c)`
\(3^{11}\times12+3^{12}\times5-3^{14}\)
`=`\(3^{11}\times\left(12+3\times5-3^3\right)\)
`=`\(3^{11}\times\left(12+15-27\right)\)
`=`\(3^{11}\times0=0\)
a) = 259 - 187 + 481 + 357
= 910
b) = 57 : 54 - 24
= 53 - 24
= 125 - 16
= 109
a/\(-\left(-432-3x\right)+\left(-432-4x+21\right)=-2345\)
\(\Leftrightarrow+432+3x-432-4x+21=-2345\)\(\Leftrightarrow\left[432+\left(-432\right)\right]+\left[\left(-4x\right)+3x\right]+21=-2345\)
\(\Leftrightarrow0+-1x+21=-2345\)\(\Leftrightarrow-1x=-2345-21=-2366\)
\(\Rightarrow x=\left(-2366\right):\left(-1\right)=2366\)
b/\(12x-\left(-3546-3x\right)=\left(2x-234\right)-\left(-678-2x\right)\)
\(\Leftrightarrow12x+3546+3x=2x-234+678+2x\)
\(\Leftrightarrow15x+3546=\left(2x+2x\right)+\left[\left(-234\right)+678\right]\)
\(\Leftrightarrow15x+3546=4x+444\)
\(\Leftrightarrow15x+3546-4x-444=0\)
\(\Leftrightarrow\left(15x-4x\right)+\left(3546-444\right)=0\)
\(\Leftrightarrow11x+3102=0\)
\(\Leftrightarrow11x=0-3102=-3102\)
\(\Rightarrow x=\left(-3102\right):11=-282\)
5 x y - 270 = 1365 ( 2 x y + 76 ) x 2 = 432 - 7 x 8
5 x y = 1365 + 270 ( 2 x y + 76 ) x 2 = 432 - 56
5 x y = 1535 ( 2 x y + 76 ) x 2 = 376
y = 1635 : 5 2 x y + 76 = 376 : 2
y = 327 2 x y + 76 = 188
Vậy y = 327 2 x y = 188 - 76
2 x y = 112
y = 112 : 2
y = 56
\(5\times y-270=1365\)
\(\Rightarrow5\times y=1365+270\)
\(\Rightarrow5\times y=1635\)
\(\Rightarrow y=1635:5\)
\(\Rightarrow y=327\)
4/21
D 4/21