A= \(x = {3^2 \over 3.7}+{3^2 \over 7.9}+{3^2 \over 9.22}+{3^2 \over 11.26}+{3^2 \over 13.30}\)(ko dùng máy tính) giả giùm v heheh)
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VN
7 tháng 2 2020
a, 8/x-8 + 11/x-11 = 9/x-9 + 10/ x-10
b, x/x-3 - x/x-5 = x/x-4 - x/x-6
c, 4/x^2-3x+2 - 3/2x^2-6x+1 +1 = 0
d, 1/x-1 + 2/ x-2 + 3/x-3 = 6/x-6
e, 2/2x+1 - 3/2x-1 = 4/4x^2-1
f, 2x/x+1 + 18/x^2+2x-3 = 2x-5 /x+3
g, 1/x-1 + 2x^2 -5/x^3 -1 = 4/ x^2 +x+1
3 tháng 6 2019
\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)
\(=3^2.2.\left(\frac{1}{10.14}+\frac{1}{14.18}+\frac{1}{18.22}+\frac{1}{22.26}+\frac{1}{26.30}\right)\)
\(=9.2.\frac{1}{4}.\left(\frac{14-10}{14.10}+\frac{18-14}{14.18}+\frac{22-18}{18.22}+\frac{26-22}{22.26}+\frac{30-26}{26.30}\right)\)
\(=\frac{9}{2}\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+\frac{1}{18}-\frac{1}{22}+\frac{1}{22}-\frac{1}{26}+\frac{1}{26}-\frac{1}{30}\right)\)
=\(\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{30}\right)=\frac{9}{2}.\frac{1}{15}=\frac{3}{10}\)
XO
3 tháng 6 2019
\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{13.30}\)
= \(2.\left(\frac{3^2.}{5.2.14}+\frac{3^2}{2.7.18}+\frac{3^2}{2.9.22}+\frac{3^2}{2.13.30}\right)\)
= \(2.\left(\frac{3^2}{10.14}+\frac{3^2}{14.18}+\frac{3^2}{18.22}+\frac{3^2}{26.30}\right)\)
= \(2.\frac{3^2}{4}\left(\frac{4}{10.14}+\frac{4}{14.18}+\frac{4}{18.22}+\frac{4}{26.30}\right)\)
= \(\frac{9}{2}\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+\frac{1}{18}-\frac{1}{22}+\frac{1}{195}\right)\)
= \(\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{22}+\frac{1}{195}\right)\)
= \(\frac{9}{2}.\left(\frac{3}{55}+\frac{1}{195}\right)\)
=\(\frac{9}{2}.\frac{128}{2145}\)
= \(\frac{192}{715}\)
HN
tính: A = \(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)
0
HN
1
AK
12 tháng 4 2018
\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{99.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)
\(=\frac{9}{5.14}+\frac{9}{7.18}+\frac{9}{9.22}+\frac{9}{11.26}+\frac{9}{13.30}\)
\(=\frac{9}{2}.\left(\frac{4}{10.14}+\frac{4}{14.18}+\frac{4}{18.22}+\frac{4}{22.26}+\frac{4}{26.30}\right)\)
\(=\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+...+\frac{1}{26}-\frac{1}{30}\right)\)
\(=\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{30}\right)\)
\(=\frac{9}{2}.\left(\frac{3}{30}-\frac{1}{30}\right)\)
\(=\frac{9}{2}.\frac{2}{30}\)
\(=\frac{9}{30}\)
\(=\frac{3}{10}\)
Chúc bạn học tốt !!!
