tinh 11x325x37-915 phan (2x314)2
giup minh ne 10 phep tinh nhan so thap phan, phan thap phan co 2 chu so
10 phep tinh phan thap phan co 3 chu so
10 phep tinh so thap cong so thap phan
10 phep tinh so thap phan tru so thap phan
tinh tong
s = 2 phan 4 + 2 phan 12 + 2 phan 24 + ........... + 2 phan 4900
tinh tong
s = 2 phan 4 + 2 phan 12 + 2 phan 24 + ....... + 2 phan 4900
S=\(\dfrac{2}{4}+\dfrac{2}{12}+\dfrac{2}{24}+...+\dfrac{2}{4900}\)
S=\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{2450}\)
S=\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{49.50}\)
S=\(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{49}-\dfrac{1}{50}\)
S=\(1-\dfrac{1}{50}=\dfrac{49}{50}\)
Vậy S=\(\dfrac{49}{50}\)
\(S=\dfrac{2}{4}+\dfrac{2}{12}+\dfrac{2}{24}+...+\dfrac{2}{4900}\)
\(S=\dfrac{2}{2.2}+\dfrac{2}{2.6}+\dfrac{2}{4.6}+...+\dfrac{2}{50.98}\)
\(\Rightarrow\dfrac{1}{2}S=\dfrac{2}{2.4}+\dfrac{2}{4.6}+\dfrac{2}{6.8}+...+\dfrac{2}{98.100}\)
\(\dfrac{1}{2}S=\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{8}+...+\dfrac{1}{98}-\dfrac{1}{100}\)
\(\dfrac{1}{2}S=\dfrac{1}{2}-\dfrac{1}{100}\)
\(\dfrac{1}{2}S=\dfrac{49}{100}\)
\(\Rightarrow S=\dfrac{49}{100}:\dfrac{1}{2}\)
\(\Rightarrow S=\dfrac{49}{50}\)
tinh :
4 phan 7* 5 phan 6 +5 phan 7 *5 phan 6 ; 1 phan 2 :3 * 1 phan 2
tinh :
4 phan 7* 5 phan 6+ 5 phan 7 * 5 phan 6 ; 1 phan 2 chia 3 * 1 phan 2
\(\frac{4}{7}x\frac{5}{6}+\frac{5}{7}x\frac{5}{6}\)
\(=\frac{5}{6}x\left(\frac{4}{7}+\frac{5}{7}\right)=\frac{5}{6}x\frac{9}{7}=\frac{45}{42}=\frac{15}{14}\)
\(\frac{1}{2}:3x\frac{1}{2}=\frac{1}{6}x\frac{1}{2}=\frac{1}{12}\)
Dat tinh roi tinh ( phan thap phan cua thuong lay den 2 chu so ) 343,673:1,57
bằng 218,9 nha bạn
k cho mình nha =]
915×37+63×915
915 x 37 + 63 x 915
= 915 x (37 + 63)
= 915 x 100
= 91 500
tinh
7 phan 12 - 2 phan 7 + 1 phan 12
12 phan 12 - 5 phan 17 - 4 phan 17
\(\frac{7}{12}-\frac{2}{7}+\frac{1}{12}\)=\(\frac{25}{84}\)+\(\frac{1}{12}\)=\(\frac{8}{21}\)
\(\frac{12}{12}-\frac{5}{17}-\frac{4}{17}=\frac{12}{17}-\frac{4}{17}=\frac{8}{17}\)
tinh nhanh 4 phan 5 cong 2 phan 7 cong 11 phan 5 cong 12 phan 7 cong 1 phan 5
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\frac{4}{5}+\frac{11}{5}+\frac{1}{5}+\frac{2}{7}+\frac{12}{7}\)
\(=\frac{4+11+1}{5}+\frac{2+12}{7}\)
\(=\frac{16}{5}+\frac{14}{7}\)
\(=\frac{16}{5}+2=\frac{26}{5}\)
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\left(\frac{4}{5}+\frac{11}{5}+\frac{1}{5}\right)+\left(\frac{2}{7}+\frac{12}{7}\right)\)
\(=\frac{16}{5}+\frac{14}{7}\)
\(=\frac{16}{5}+2=\frac{16}{5}+\frac{10}{5}=\frac{26}{5}\)
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\left(\frac{4}{5}+\frac{11}{5}+\frac{1}{5}\right)+\left(\frac{2}{7}+\frac{12}{7}\right)\)
\(=\frac{16}{5}+2\)
\(=\frac{26}{5}\)
tinh
2 - 5 phan 6
7 phan 8 + 3 phan 4
2 phan 5 + 3 phan 4
7 phan 12 - 2 phan 7 + 1 phan 12
12 phan 17 - 5 phan 17 - 4 phan 17
2 - 5/6= 7/6
7/8+3/4=`13/8
2/5+3/4=23/20
7/12 - 2/7 + 1/12=8/21
12/17 - 5/17 - 4/17=3/17
\(2-\frac{5}{6}=1\frac{1}{6}\)
\(\frac{7}{8}+\frac{3}{4}=1\frac{5}{8}\)
\(\frac{2}{5}+\frac{3}{4}=\frac{23}{20}\)
\(\frac{7}{12}-\frac{2}{7}+\frac{1}{12}=\frac{8}{7}\)
\(\frac{12}{17}-\frac{5}{17}-\frac{4}{17}=\frac{3}{17}\)