CHUNG MINH RANG :
A = 1. 3 . 5 . ..... . 55 + 11 chia het cho 11
Cho A = 119+118+117+........+11+1
Chứng minh A \(⋮\) 5
cho 8a+3b chia het 11.
cmr:2a+9b chia het 11
rút gọn
a) \(\frac{11^4.6-11^5}{11^4-11^5}\)
b ) \(\frac{9^8.3-3^{18}}{9^8.5+9^8.7}\)
c ) \(\frac{10^5-10^5.3}{10^5.11}\)
*Phép chia
a)\(11\dfrac{1}{4}-\left(2\dfrac{5}{7}+5\dfrac{1}{4}\right)\)
b)\(\left(8\dfrac{5}{11}+3\dfrac{5}{8}\right)-3\dfrac{5}{11}\)
c)\(\dfrac{-1}{4}.13\dfrac{9}{11}-0,25.6\dfrac{2}{11}\)
d)\(\dfrac{4}{9}:\left(\dfrac{-1}{7}\right)+6\dfrac{5}{9}:\left(\dfrac{-1}{7}\right)\)
Tính hợp lí
a)\(11.\dfrac{1}{4}-\left(2\dfrac{5}{7}+5\dfrac{1}{4}\right)\)
b)\(\left(8\dfrac{5}{11}+3\dfrac{5}{8}\right)-3\dfrac{5}{11}\)
c)\(-\dfrac{1}{4}.13\dfrac{9}{11}-0,25.6\dfrac{2}{11}\)
d)\(\dfrac{4}{9}:\left(-\dfrac{1}{7}\right)+6\dfrac{5}{9}:\left(-\dfrac{1}{7}\right)\)
chung minh
1 + 4 + 4 mu2 +........+ 4 mu 11 : het cho 5 va 21
7 + 7 mu 2 + 7 mu 3 +.....+ 7 mu 102 : het cho 8
Tính
a,A = [3 × (-7)^7 -10× (-7)^7] : (-7)^6
b,B= (-11)^9 : [ 5 × (-11)^5 - 16 × (-11)^5
c,C= (-125)×25×(-32)
Rút gọn
1.\(\frac{7}{19}.\frac{8}{11}+\frac{7}{19}.\frac{3}{11}+\frac{12}{19}\)
2.\(\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{9}-\frac{2}{11}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{9}-\frac{4}{11}}\)
