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315/316*313/314*316/315*317/313
=315*313*316*317/316*314*315*313
=317/314
Tick cho mik nha
1/
Tổng A là tổng các số hạng cách đều nhau 4 đơn vị.
Số số hạng: $(101-1):4+1=26$
$A=(101+1)\times 26:2=1326$
2/
$B=(1+2+2^2)+(2^3+2^4+2^5)+(2^6+2^7+2^8)+(2^9+2^{10}+2^{11})$
$=(1+2+2^2)+2^3(1+2+2^2)+2^6(1+2+2^2)+2^9(1+2+2^2)$
$=(1+2+2^2)(1+2^3+2^6+2^9)$
$=7(1+2^3+2^6+2^9)\vdots 7$
\(a,2^2=4,2^3=8,2^4=16,2^5=32,2^6=64,2^7=128,2^8=256,2^9=512,2^{10}=1024\)
\(b,3^2=9,3^3=27,3^4=81,3^5=243\)
\(c,4^2=16,4^3=64,4^4=256\)
\(d,5^2=25,5^3=125,5^4=625\)
a) \(3.5^2+15.2^2-26\div2\)
= 3.25 + 15.4 - 13
= 75 + 60 - 13
= 135 - 13
= 122
b) \(5^3.2-100\div4+2^3.5\)
= 125.2 - 25 + 8.5
= 250 - 25 + 40
= 225 + 40
= 265
c)\(6^2\div9+50.2-3^3.33\)
= 36 : 9 + 100 - 9.33
= 4 + 100 - 297
= 104 - 297
= -193
d)\(3^2.5+2^3.10-81\div3\)
= 9.5 + 8.10 - 27
= 45 + 80 - 27
= 125 - 27
= 98
e) \(5^{13}\div5^{10}-25.2^2\)
= 53 - 25.4
= 125 - 100
= 25
f) \(20\div2^2+5^9\div5^8\)
= 20 : 4 + 5
= 5 + 5
= 10
a) [ 316 – ( 25 . 4 + 16 )] : 8 – 24
=( 316 – 116 ) : 8 – 24 = 200 ∶ 8 – 24 = 25 – 24 = 1
b) | -15| + (-27) + 8 + | - 23|
= 15 – 27 + 8 + 23 = 19
c) 5 8 : 5 6 + 2 2 . 3 3 - 2010 0 = 5 2 + 4 . 27 – 1 = 25 + 108 – 1 = 132
G = 21 + 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 210
2.G = 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 210 + 211
2G - G = (22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 210 + 211) - (21 + 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 210)
G = 22 + 23 + 24 +25 + 26 + 27 + 28 + 29 + 210 + 211 - 21 -22 -23 -24 - 25 - 26 - 27 - 28 - 29 - 210
G = (22 -22) +(23 - 23) + (24 - 24) + (25 -25) + (26 - 26) +(27 - 27) +(28 -28) + (29 - 29) + (210 - 210) + (211 - 21)
G = 211 - 2
G = 2048 - 2 (đpcm)
b,
G = 21 + 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29 + 210
D = 2.(1+ 2 + 22 + 23 + 24 + 25 + 26 + 27 + 28 + 29)
Vì 2 ⋮ 2 nên D = 2.(1+2+22+23+24+25+26+27+28+29)⋮2 (đpcm)
\(A=2\left(1+2\right)+...+2^7\left(1+2\right)=3\left(2+...+2^7\right)⋮3\)
a) \(A=1+2+2^2+...+2^{50}\)
\(\Rightarrow2A=2+2^2+...+2^{51}\)
\(\Rightarrow A=2A-A=2+2^2+...+2^{51}-1-2-2^2-...-2^{50}=2^{51}-1\)
b) \(B=1+3+3^2+...+3^{100}\)
\(\Rightarrow3B=3+3^2+...+3^{101}\)
\(\Rightarrow2B=3B-B=3+3^2+...+3^{101}-1-3-3^2-...-3^{100}=3^{101}-1\)
\(\Rightarrow B=\dfrac{3^{101}-1}{2}\)
c) \(C=5+5^2+...+5^{30}\)
\(\Rightarrow5C=5^2+5^3+...+5^{31}\)
\(\Rightarrow4C=5C-C=5^2+5^3+...+5^{31}-5-5^2-...-5^{30}=5^{31}-5\)
\(\Rightarrow C=\dfrac{5^{31}-5}{4}\)
d) \(D=2^{100}-2^{99}+2^{98}-...+2^2-2\)
\(\Rightarrow2D=2^{101}-2^{100}+2^{99}-...+2^3-2^2\)
\(\Rightarrow3D=2D+D=2^{101}-2^{100}+2^{99}-...+2^3-2^2+2^{100}-2^{99}+...+2^2-2=2^{101}-2\)
\(\Rightarrow D=\dfrac{2^{101}-2}{3}\)