Tính nhẩm:
6 : 3 9 : 3 12 : 3 | 15 : 3 3 : 3 21 : 3 | 30 : 3 27 : 3 18 : 3 |
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4:
a: \(\dfrac{\left(158-x\right)}{7}=20\)
=>\(158-x=7\cdot20=140\)
=>x=158-140=18
b: \(2x-138=23\cdot32\)
=>\(2x-138=736\)
=>2x=736+138=874
=>x=437
c: \(231-\left(x-6\right)=\dfrac{1339}{13}\)
=>\(231-\left(x-6\right)=103\)
=>x-6=128
=>x=128+6=134
d: \(10+2x=\dfrac{45}{43}\)
=>\(2x=\dfrac{45}{43}-10=-\dfrac{385}{43}\)
=>\(x=-\dfrac{385}{43}:2=-\dfrac{385}{86}\)
e: \(70-5\left(2x-3\right)=45\)
=>\(5\left(2x-3\right)=70-45=25\)
=>2x-3=5
=>2x=8
=>x=4
g: \(156-\left(x+61\right)=82\)
=>x+61=156-82=74
=>x=74-61=13
a) 67+135+33=(67+33)+135=100+135=235
b) 277+13+323+87=(277+323)+(113+87)=600+200=800
c) 29+132 + 237 + 868 + 763=29+(132+868)+(237+763)=29+1000+1000=2029
d) 652 + 327 + 148 + 15 + 73=(652+148)+(327+73)+15=800+400+15=1215
e) 463 + 318 + 137 + 22=(463+137)+(318+22)=600+340=940
g) 189 + 424 +511 + 276 + 55=(189+511)+(424+276)+55=700+700+55=1455
h) (321 +27) + 79=(321+79)+27=400+27=427
i) 185+434+515+266+155=(185+515)+(434+266)+155=700+700+155=1555
k) 168 + 79 + 132=(168+132)+79=300+79=379
l) 29 + 132 + 237 + 868 + 763=29+(132+868)+(237+763)=29+1000+1000=2029
\(\dfrac{3}{17}\) .\(\dfrac{6}{29}\) - \(\dfrac{3}{17}\).\(\dfrac{35}{29}\) + 2022\(\dfrac{3}{17}\)
= (\(\dfrac{3}{17}\).\(\dfrac{6}{29}\) - \(\dfrac{3}{17}\).\(\dfrac{35}{29}\)) + 2022 + \(\dfrac{3}{17}\)
= \(\dfrac{3}{17}\).(\(\dfrac{6}{29}\) - \(\dfrac{35}{29}\)) + 2022 + \(\dfrac{3}{17}\)
= \(\dfrac{3}{17}\).(-1) + 2022 + \(\dfrac{3}{17}\)
= (- \(\dfrac{3}{17}\) + \(\dfrac{3}{17}\)) + 2022
= 0 + 2022
= 2022
b; \(\dfrac{5}{6}\) - (\(\dfrac{1}{3}\) + \(\dfrac{1}{2}\)).20%
= \(\dfrac{5}{6}\) - \(\dfrac{5}{6}\).\(\dfrac{1}{5}\)
= \(\dfrac{5}{6}-\dfrac{1}{6}\)
= \(\dfrac{4}{6}\)
= \(\dfrac{2}{3}\)
Tổng trên có số số hạng là:
(327 - 3) : 3 + 1 = 109 (số)
Tổng là;
(327 + 3) x 109 : 2 = 17985
x chia hết cho 2 và 3
nên x thuộc BC(2;3)
=>x thuộc B(6)
mà 312<x<330
nên \(x\in\left\{318;324\right\}\)
6 : 3 = 2
9 : 3 = 3
12 : 3 = 4
15 : 3 = 5
3 : 3 = 1
21 : 3 = 7
30 : 3 = 10
27 : 3 = 9
18 : 3 = 6