\(C=\frac{4}{3x7}+\frac{4}{7x11}+\frac{4}{11x15}+\frac{4}{15x19}+\frac{4}{19x23}+\frac{4}{23x27}\)
= 1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27
=1/3-(1/7+1/7)-(1/11+1/11)-(1/15-1/15)-(1/19+1/19)-(1/23-1/23)-1/27
=1/3-1/27
=...
=8/27
4/3x7 + 4/7x11 + 4/11x14 + 4/15x19 + 4/19x23 + 4/23x27
Tính nhanh A = 4/3x7 + 4/7x11 + 4/11x15 + 4/15x19 + 4/19x23 + 4/23x27
Tính nhanh
4/3x7 - 4/7x11+4/11x15 - 4/15x19 + 4/19x23 - 4/23x27
giúp mình với !!!!!!!!!!!
4/3x7 + 4/7x11 + 4/11x15 + 4/15x9 + 4/19x23 + 4/23x27
\(\frac{12}{3x7}+\frac{12}{7x11}+\frac{12}{11x15}+..........+\frac{12}{39x43}+\frac{12}{43x47}\)
Các bn làm cả cách giải giúp mh nha !!!!!!!!!!!!!!!!!!!!!!!!
B1:Tính
a)\(3\frac{4}{7}x2\frac{4}{5}\)
b)\(\frac{4}{5}:\frac{1}{2}+\frac{17}{3}\)
c)\(5\frac{1}{3}-2\frac{1}{6}\)
d)\(4\frac{1}{2}:2\frac{1}{4}\)
\(\frac{1}{2}-\frac{1}{3}-\frac{2}{3}+\frac{1}{4}+\frac{2}{4}+\frac{3}{4}-\frac{1}{5}-\frac{2}{5}-\frac{3}{5}-\frac{4}{5}+...+\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+...+\frac{9}{10}\)\(+\)\(\frac{9}{10}\)
1. Tính nhanh
a) \(\frac{8}{7}\times\frac{2}{5}+\frac{6}{7}\times\frac{2}{5}=\)
b) \(\frac{40}{11}\times\frac{4}{7}-\frac{4}{7}\times\frac{7}{11}=\)
c)\(\frac{3}{4}\times\frac{6}{15}\times\frac{4}{3}=\)
d) \(\frac{1}{2}\times\frac{2}{3}\times\frac{4}{5}\times\frac{2}{3}\times\frac{5}{4}=\)
giúp mình nha mình cần gấp lắm
Tính nhanh bài toán sau
\(\left(\frac{19}{20}x\frac{3}{4}+\frac{1}{20}x\frac{3}{4}\right)x\left(\frac{1}{2}x\frac{3}{4}-\frac{2}{4}x\frac{3}{4}\right)\)
