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64 x 25 + 35 x 25 + 25
= ( 64 + 35 + 1 ) x 25
= 100 x 25
= 2500
\(\frac{13}{38}\)và \(\frac{21}{64}\)
Vì \(\frac{13}{38}\)\(>\)\(\frac{13}{39}\)\(=\)\(\frac{1}{3}\)\(;\)\(\frac{1}{3}\)\(=\)\(\frac{21}{63}\)\(>\)\(\frac{21}{64}\)nên \(\frac{13}{38}\)\(>\)\(\frac{21}{64}\).
A x 2 = 1 + 1/2+1/4+1/8+1/16+1/32
A x 2 - A = (1 + 1/2+1/4+1/8+1/16+1/32 ) - ( 1/2+1/4+1/8+1/16+1/32 +1/64)
A = 1 - 1/64
A = 63/64
#)Giải :
\(\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)
\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}-\frac{1}{64}+\frac{1}{64}-\frac{1}{128}\)
\(=\frac{1}{2}-\frac{1}{128}\)
\(=\frac{63}{128}\)
tinh nhanh :
52 x 64 + 520 x 7 - 52 x 34 = 52 x 64 + 52 x 10 x 7 - 52 x 34
=52 x ( 64 + 70 - 34 ) = 5200
52 x 64 + 520 x 7 - 52 x 34
= 52 x 64 + 52 x 10 x 7 - 52 x 34
=. 52 x 64 + 52 x 70 - 52 x 34
=52 x( 64 + 70 - 34 )
=52 x 100 = 5200
k nha
\(1+\frac{5}{4}+\frac{5}{8}+\frac{5}{16}+\frac{5}{32}+\frac{5}{64}\)
\(=\frac{64}{64}+\frac{80}{64}+\frac{40}{64}+\frac{20}{64}+\frac{10}{64}+\frac{5}{64}\)
\(=\frac{64+80+40+20+10+5}{64}\)
\(=\frac{219}{64}\)
\(=\frac{27}{8}\)
1+5/4+5/8+5/16+5/32+5/64
=1+5/4+5/8+5/16+5/32+5/64
=1+(5/4+5/8+5/16+5/32+5/64)
=1+[5x(1/4+1/8+1/16+1/32+1/64)]
A=1/4+1/8+1/16+1/32+1/64
2A=1/2+1/4+1/8+1/16+1/32
2A-A=(1/2+1/4+1/8+1/16+1/32)+(1/4+1/8+1/16+1/32+1/64)
A=1/2-1/64
A=31/64
1+[5x31/64]
=1+155/64
=219/64
\(=39x64-21.39+21x39+21x64\)
\(=39x64+21x64\)(2 số đối nhau bỏ đi nhoa!)
\(=64x\left(39+21\right)\)
\(=64x60\)
\(=3840\)
Chúc em học tốt^^