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a) 41. 36+ 59. 90 + 41. 84 + 59. 30
= 41 . (36 + 84) + 59 . (90 + 30)
= 41 . 120 + 59 . 120
= 120 . ( 41 + 59 )
= 120 . 100
= 12000
b) 4. 51 . 7 + 2 . 86 .7 + 6 . 4 . 7
= 28 . 51 + 2 . 43 . 2 . 7 + 6 . 4 . 7
= 28 . 51 + 28 . 43 + 28 . 6
= 28 . ( 51 + 43 + 6 )
= 28 . 100
= 2800
c) ( 4.7 ) . 5 + ( 4.7 ) . 43 + ( 4.7) - 6
= 28 . 5 + 28 .43 + 28 - 6
= 28 . (5 + 43 + 1) - 6
= 28 . 49 - 6
= 1372 - 6
= 1366.
d) 53 . 39 + 47 . 39 - 53 . 21 - 47 . 21
= 53 . (39 - 21) + 47. (39 - 21)
= (39 - 21) . ( 53 + 47 )
= 18 . 100
= 1800.
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3:
a:Các tia trên hình là Ax,Ay,Bx,By,Cx,Cy
=>Có 6 tia
b: AB<AC
=>B nằm giữa A và C
=>AB+BC=AC
=>BC=4cm
c: AI=3/2=1,5cm
CI=7-1,5=5,5cm
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a, 19.64 + 76.34
= 19.64 + 19.4.34
= 19.64 + 19.136
= 19.(64 + 136)
= 19.200
= 3800
b, 35.12 + 65.13
= 35.12 + 65.12 + 65
= 12.(35+65) + 65
= 12.100 + 65
= 1200 + 65
= 1265
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đặt \(A=2^{100}-2^{99}-2^{98}-....-2-1\)
\(=2^{100}-\left(2^{99}+2^{98}+....+2+1\right)\)
Đặt \(B=2^{99}+2^{98}+.....+2+1\)
\(2B=2^{100}+2^{99}+...+2^2+2\)
\(B=2B-B=2^{100}-1\)
\(A-B=2^{100}-\left(2^{100}-1\right)=2^{100}-2^{100}+1=1\)
Vậy A = 1
\(2^{100}-2^{99}-2^{98}-....-2-1\)
đặt \(A=2^{100}-2^{99}-2^{98}-....-2-1\)
\(A=2^{100}-\left(2^{99}+2^{98}+.....+2+1\right)\)
đặt \(B=2^{99}+2^{98}+...+2+1\)
\(B=1+2+....+2^{98}+2^{99}\)
\(2B=2+2^2+.....+2^{99}+2^{100}\)
\(2B-B=2+2^2+....+2^{99}+2^{100}-\left(1+2+....+2^{98}+2^{99}\right)\)
\(B=2+2^2+....+2^{99}+2^{100}-1-2-....-2^{98}-2^{99}\)
\(B=2^{100}-1\)
ta có \(A=2^{100}-\left(2^{100}-1\right)\)
\(\Rightarrow A=2^{100}-2^{100}+1\)
\(\Rightarrow A=0+1\)
\(\Rightarrow A=1\)
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