\(E=\dfrac{1}{1\times2}+\dfrac{2}{2\times4}+\dfrac{3}{4\times7}+\dfrac{4}{7\times11}+\dfrac{5}{11\times16}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\)
\(=1-\dfrac{1}{16}=\dfrac{15}{16}\)
#kễnh
A=1/1x2 + 2/2x4 + 3/4x7 + 4/7x11 + 5/11x16 + 6/16x22 + 7/22x29=....?
tính nhanh
a 1/2+2/2x4+3/4x7+4/7x11+5/11x16
b 3/54+4/117+5/234+6/432+7/744
1/1x2+2/2x4+3/4x7+4/7x11+...+11/56x67
1/1x2 + 2/2x4 + 3/4x7 + 4/7x11 +......+ 11/56x67
Help meeee !
Tính tổng của phép tính sau :
1/1x2 + 2/2x4 + 3/4x7 + 4/7x11 +...+ 8/29x37 + 9/37x46 = ?
Hỡi các thiên tài toán học, hãy giúp mình lần này !
Trân trọng cảm ơn
tính tổng
S= \(\frac{4}{1+2}\)+\(\frac{4}{1+2+3}\)+\(\frac{4}{1+2+3+4}\)+...+\(\frac{4}{1+2+3+...+100}\)
O=\(\frac{1}{1x2}\)+\(\frac{2}{2x4}\)+\(\frac{3}{4x7}\)+\(\frac{4}{7x11}\)+\(\frac{5}{11x16}\)
X=\(\frac{3}{54}\)+\(\frac{5}{126}\)+\(\frac{7}{294}\)+\(\frac{8}{609}\)
giúp mình nha
Ai nhanh mình sẽ tick
A=5/1x6+5/6x11+5/11x16+5/16x21+...+5/101x106
B=3/1x4+3/4x7+3/7x10+....+3/97x100
C=1/2x7+1/7x12+1/12x17+....+1/97x102
D=1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
E=3/2x4+3/4x6+3/6x8+....+3/98x100
\(\frac{2}{11x16}\)+\(\frac{2}{16x21}\)+.................+\(\frac{2}{61x66}\)
\(\frac{2}{5x7}\)+\(\frac{4}{7x11}\)+\(\frac{3}{11x14}\)+\(\frac{4}{14x18}\)+\(\frac{5}{18x23}\)+\(\frac{7}{23x30}\)
hãy tính nhanh hai phép tính trên
K=4 /1x4 + 4 /4x7 + 4 /7x11+ .............+4 / 100x 103
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