(25.4+65.7):5-2.(152:8-320:16)
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[516-(25.4 +16)]:8-68
\(\left[516-\left(25\cdot4+16\right)\right]:8-68\)
\(=\dfrac{\left[516-100-16\right]}{8}-68\)
\(=\dfrac{400}{8}-68=50-68=-18\)
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Điền dấu >, <, =
13500 … 135 ×100
257 … 8762 ×0
26 ×11 … 280
320 : 16×2)=320:16:2
1600 : 10 … 1006
15 ×8×37…37×15×8
13500 = 135 ×100
257 > 8762 ×0
26 ×11 > 280
320 : 16×2=320:16:2
1600 : 10 < 1006
15 ×8×37=37×15×8
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Điền dấu >, <, =
13500 … 135 ×100
257 … 8762 ×0
26 ×11 … 280
320 : 16×2)=320:16:2
1600 : 10 … 1006
15 ×8×37…37×15×8
13500 = 135 ×100
257 > 8762 ×0
26 ×11 > 280
320 : 16×2=320:16:2
1600 : 10 < 1006
15 ×8×37=37×15×8
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Giúp tớ vs Tính nhanh a) -3/25.4/17.5/-3.17/2 B)-8/15.13/16:13/30 C)3/11.2/9.-8/33+3/11.7/9 D)-11/25.2/3- -1/6+ -2/3.14/15(âm1/6)
a: \(\dfrac{-3}{25}\cdot\dfrac{4}{17}\cdot\dfrac{5}{-3}\cdot\dfrac{17}{2}=\dfrac{4}{17}\cdot\dfrac{17}{2}\cdot\dfrac{3}{25}\cdot\dfrac{5}{3}=2\cdot\dfrac{1}{5}=\dfrac{2}{5}\)
b: \(=-\dfrac{8}{15}\cdot\dfrac{13}{16}\cdot\dfrac{30}{13}=\dfrac{-8}{15}\cdot\dfrac{15}{8}=-1\)
c: \(=\dfrac{3}{11}\left(\dfrac{2}{9}\cdot\dfrac{-8}{33}+\dfrac{7}{9}\right)=\dfrac{3}{11}\cdot\dfrac{215}{297}=\dfrac{2015}{1089}\)
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Tính nhanh
295-(31+4*5*2)
152*(652-552+40*58)
2984-(16*35-5*16)
1122:11+720:8-111
thực hiện các phép tính
a,18+25.4-4^3
b,275-(49+125:5^3
c,2015+(8.15-(18-8)^2)
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) \(2015+\left(8\times15-\left(18-8\right)^2\right)\)
\(=2015+\left(8\times15-\left(10\right)^2\right)\)
\(=2015+\left(8\times15-100\right)\)
\(=2015+\left(120-100\right)\)
\(=2015+20\)
\(=2035\)
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1/2 + 1/4 + 1/8 + 1/16 + ............ + 1/152
Đặt tổng trên = A
\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{152}\)
\(Ax2=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{76}\)
\(Ax2-A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{76}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{152}\right)\)
\(A=1-\frac{1}{152}\)
\(A=\frac{151}{152}\)
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\(\text{Đặt tổng trên = A}\)
\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{152}\)
\(Ax2=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{76}\)
\(Ax2-A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{76}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{16}+...+\frac{1}{152}\right)\)
\(A=1-\frac{1}{152}\)
$A=\frac{151}{152}$
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1,Tính giá trị biểu thức
a, 13 . 17 - 256 : 16 + 14 : 7 - 1
b, 15 . 24 - 14 . 5 . (145 : 5 - 27)
c, 15 . 8 - (17 - 30 + 83) - 144 : 6
d,18 - 4 . (27 - 90 + 73) : 10
2,Tìm x
a, 315 - (135 - x)=215
b, x - 320 : 32 = 25 . 16
c, 3 . x - 2018 : 2 = 23
d, 280 - 9 . x - x = 80
e, 38 . x - 12 . x - x . 16 = 40
Giúp mình với nhé,mình đang cần gấp !!
2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)
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Tính nhẩm:
a) 125 . 10; b) 2 021 . 100
c) 1 991. 25.4; d) 3025 .125 . 8
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
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