\(A=\frac{6}{5.8}+\frac{6}{8.11}+....+\frac{6}{87.90}\)
\(A=2.\left(\frac{3}{5.8}+\frac{3}{8.11}+....+\frac{3}{87\cdot90}\right)\)
\(A=2.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+....+\frac{1}{87}-\frac{1}{90}\right)\)
\(A=2.\left(\frac{1}{5}-\frac{1}{90}\right)\)
\(A=2.\frac{1}{6}=\frac{1}{3}\)
Tính:
\(A=\frac{6}{2x5}+\frac{6}{5x8}+\frac{6}{8x11}+...+\frac{6}{47x50}\)
Tính
a)S1=2/3x5+2/5x7+2/7x9+...+2/97x99
b)S2=6/2x5+6/5x8+6/8x11+...+6/29x32
Bài 1: tính:
A=3x4+4x5+5x6+...+58x59+59x60
Bài 2: Tính:
A=2x4+4x6+6x8+...+96x98+98x100
bài 3: tính:
B=2x3+5x8+8x11+...+89x92+92x95
bài 4: tính:
C=3x4x5+4x5x6+5x6x7+...+20x21x22+21x22x23
bài 5: tính:
C=2x4x6+4x6x8+...+20x22x24+22x24x26
bài 6: tính:
C=1x4x7+4x7x10+...+21x24x27+24x27x30
bài 7: tính:
A=3x7x11+7x11x15+...+23x27x31+27x31x35
bài 8: tính:
A=1x4+3x6+5x8+...+47x50+49x52
bài 9: tính:
A=1+3+6+10+...+4851+4950
AI LÀM HỢP LÝ MÌNH SẼ TICK CHO NHA...
CỐ LÊN...
tinh cac tong sau:B8=6/15x18+6/18x21+6/21x24+...+6/87x90
6/15 x18+6/18x24+6/21x24+.....+6/87x90
A=3/5x8+3/8x11+3/11x14+...+3/2006x2009
\(\frac{3}{2x5}\)+ \(\frac{3}{5x8}\)+ \(\frac{3}{8x11}\)+ ... + \(\frac{3}{\left(X-3\right)xX}\)= \(\frac{1}{6}\)
Giúp mk nhé!!!
A= 1/2X5-1/5X8-1/8X11-...-1/92X95-1/95X98
B = 3/2x5 + 3/5x8 + 3/8x11 + ... +3/26x29
