1x2x3 + 2x4x6 + 3x6x9/2x3x4 + 4x6x8 + 6x9x12
1x2x3+2x4x6+3x6x9+4x8x12/2x3x4+4x6x8+6x9x12+8x12x16
tim A biet A = 1x2x3+2x4x6+4x8x12+8x16x24/2x3x4+4x6x8+8x12x16+16x24x32
Tính A\(\frac{1x2x3+2x4x6+4x8x12+8x16x24}{2x3x4+4x6x8+8x12x16+8x24x32}\)
\(A=\frac{1X2X3+2X4X6+4X8X12+8X16X24}{2X3X4+4X6X8+8X12X16+8X24X32}\)
\(A=\frac{1+1+1+1}{4+4+4+2}\)
\(A=\frac{4}{14}\)
CHÚC BẠN HỌC GIỎI !
Giúp mình giải câu hỏi này với:
1x2x3+2x3x4+3x4x5+...+100x101x102/2x4x6+4x6x8+6x8x10+...+200x202x204
Giúp mình với: 2x3x4+6x9x12/4x6x8+8x12x16
2×3×4+6×9×12/4×6×8+8×12×16
= 2×3×4×(1+3×3×3)/4×6×8×(1+2×2×2)
= 2×3×4×28/4×6×8×9
= 6×4×28/4×6×8×9
= 28/8×9 = 7/18
\(\frac{1x2x3+3x6x9+5x10x15}{2x4x6+6x12x18+10x20x30}\)
\(\frac{\frac{1}{3}+\frac{1}{7}-\frac{1}{21}+\frac{1}{35}}{\frac{2}{3}+\frac{2}{7}-\frac{2}{21}+\frac{2}{35}}\)
\(\frac{0,25+\frac{1}{9}-\frac{1}{11}}{0,75+\frac{1}{3}-\frac{3}{11}}+\frac{2}{3}\)
1/2x4x6+1/4x6x8+1/6x8x10+......+1/50x52x54
\(\frac{1}{2.4.6}+\frac{1}{4.6.8}+\frac{1}{6.8.10}+..+\frac{1}{50.52.54}\)
\(=\frac{1}{4}.\left(\frac{1}{2.4}-\frac{1}{4.6}+\frac{1}{4.6}-\frac{1}{6.8}+....+\frac{1}{50.52}-\frac{1}{52.54}\right)\)
\(=\frac{1}{4}.\left(\frac{1}{2.4}-\frac{1}{52.54}\right)\)
\(=\frac{1}{4}.\frac{175}{1404}=\frac{175}{5616}\)
Tính tổng
cho P=2x4x6+4x6x8+6x8x10+...+94x96x98+96x98x100
Ta có G = 2 . 4 + 4 . 6 + 6 . 8 + ... + 98 . 100
6 . G = 2 . 4 . 6 + 4 . 6 . 6 + 6 . 8 . 6 + .... + 98 . 100 . 6
6 . G = 2 . 4 . 6 + 4 . 6 . ( 8 - 2 ) + 6 . 8 . ( 10 - 4 ) + .... + 98 . 100 . ( 102 - 96 )
6 . G = 2 . 4 . 6 + 4 . 6 . 8 - 2 . 4 . 6 + 6 . 8 . 10 - 4 . 6 . 8 + ... + 98 .100 . 102 - 96 . 98 . 100
6 . G = 98 . 100 . 102
G = 98 . 100 . 102 : 6
G = 999 600 : 6
G = 166 600
Ta có G = 2 . 4 + 4 . 6 + 6 . 8 + ... + 98 . 100
6 . G = 2 . 4 . 6 + 4 . 6 . 6 + 6 . 8 . 6 + .... + 98 . 100 . 6
6 . G = 2 . 4 . 6 + 4 . 6 . ( 8 - 2 ) + 6 . 8 . ( 10 - 4 ) + .... + 98 . 100 . ( 102 - 96 )
6 . G = 2 . 4 . 6 + 4 . 6 . 8 - 2 . 4 . 6 + 6 . 8 . 10 - 4 . 6 . 8 + ... + 98 .100 . 102 - 96 . 98 . 100
6 . G = 98 . 100 . 102
G = 98 . 100 . 102 : 6
G = 999 600 : 6
G = 166 600
Tính tổng: 1/(2x4x6) + 1/(4x6x8) + 1/(6x8x10) +...+ 1/(96x98x100)
\(=\frac{49\times50-1}{4\times98\times100}\)