1313+41414+1414
=
=
1414/2828 + x = 1313/1010
x = ?
G= (1313/1414+10/160)-(130/140-1515/1616)
G = \(\left(\dfrac{1313}{1414}+\dfrac{10}{160}\right)-\left(\dfrac{130}{140}-\dfrac{1515}{1616}\right)\)
= \(\left(\dfrac{13}{14}+\dfrac{1}{16}\right)-\left(\dfrac{13}{14}-\dfrac{15}{16}\right)\)
= \(\dfrac{13}{14}+\dfrac{1}{16}-\dfrac{13}{14}+\dfrac{15}{16}\)
= \(\dfrac{1}{16}+\dfrac{15}{16}=1\)
Tìm x 1313/1010+x=1414/2828
Bài làm
\(\frac{1313}{1010}+x=\frac{1414}{2828}\)
\(\Rightarrow\frac{13}{10}+x=\frac{14}{28}\)
\(x=\frac{14}{28}-\frac{13}{10}\)
\(x=\frac{1}{2}-\frac{13}{10}\)
\(x=\frac{10}{20}-\frac{26}{20}\)
\(x=-\frac{16}{20}\)
\(x=-\frac{4}{5}\)
Vậy \(x=-\frac{4}{5}\)
1111+1212+1313+1414+1515+1616 / 2020+2121+2222+2323+2424+2525 =?
\(\frac{2323+1313+1414+1515+1616}{4141+2222+2323+2424+2525}\)
=\(\frac{8181}{13635}\)
Rút gọn các phân số sau:
a) − 1212 − 2424 ;
b) 120120 − 240240 ;
c) 1313 − 1414 .
a ) − 1212 − 2424 = ( − 1212 ) : ( − 1212 ) ( − 2424 ) : ( − 1212 ) = 1 2
b ) 120120 − 240240 = 120120 : ( − 120120 ) − 240240 : ( − 120120 ) = − 1 2
c) 1313 − 1414 = 1313 : ( − 101 ) − 1414 : ( − 101 ) = − 13 14
So sánh các cặp phân số sau
a.1212/1313𝑣à 1313/1414
b. 1717/2525𝑣à 515151/727272
\(\dfrac{121212}{131313}=\dfrac{121212:10101}{131313:10101}=\dfrac{12}{13}=1-\dfrac{1}{13}\)
\(\dfrac{1313}{1414}=\dfrac{1313:101}{1414:101}=\dfrac{13}{14}=1-\dfrac{1}{14}\)
Vì \(\dfrac{1}{13}>\dfrac{1}{14}\) nên \(\dfrac{12}{13}< \dfrac{13}{14}\) hay \(\dfrac{1212}{1313}< \dfrac{1313}{1414}\)
b) \(\dfrac{1717}{2525}=\dfrac{1717:101}{2525:101}=\dfrac{17}{25}=\dfrac{51}{75}\)
\(\dfrac{515151}{727272}=\dfrac{515151:10101}{727272:10101}=\dfrac{51}{72}\)
Vì \(\dfrac{51}{75}< \dfrac{51}{72}\) nên \(\dfrac{17}{25}< \dfrac{51}{72}\) hay \(\dfrac{1717}{2525}< \dfrac{515151}{727272}\)
a) \(\dfrac{1212}{1313}=\dfrac{101x12}{101x13}=\dfrac{12}{13}< \dfrac{12+1}{13+1}=\dfrac{13}{14}\)
\(\dfrac{1313}{1414}=\dfrac{101x13}{101x14}=\dfrac{13}{14}\)
Vậy \(\dfrac{1212}{1313}< \dfrac{1313}{1414}\)
Làm tương tự câu b
a) 1212/1313 = 12/13 = 1 - 1/13
1313/1414 = 13/14 = 1 - 1/14
Do 13 < 14 nên 1/13 > 1/14
⇒ 1 - 1/13 < 1 - 1/14
Vậy 1212/1313 < 1313/1414
b) 1717/2525 = 17/25
515151/727272 = 51/72 = 17/24
Do 25 > 24 nên 17/25 < 17/24
Vậy 1717/2525 < 515151/727272
1010 + 1111 +1212 + 1313 +1414 + 1515
2020 + 2121 + 2222 + 2323 + 2424 + 2525
\(\frac{1010+1111+1212+1313+1414+1515}{2020+2121+2222+2323+2424+2525}=\frac{10\times101+11\times101+12\times101+13\times101+14\times101+15\times101}{20\times101+21\times101+22\times101+23\times101+24\times101+25\times101}=\frac{101\times\left(10+11+12+13+14+15\right)}{101\times\left(20+21+22+23+24+25\right)}\)
\(=\frac{10+11+12+13+14+15}{20+21+22+23+24+25}=\frac{75}{135}=\frac{5}{9}\)
1010+1111+1212+1313+1414+1515= 7575
2020+2121+2222+2323+2424+2525= 13635
11+22+33+44+55+66+77+88+99+1010+1111+1212+1313+1414+1515+1616+.........+20162016=?
So sánh các phân số :
a ) 1212/1313 và 1313/1414 . B) 1717/2525 và 515151/727272 .
Các phân số 5/7,7/9,11/18,23/28 xếp theo thứ tự từ lớn đến bé
A)1212/1313<1313/1414.B)1717/2525<515151/727272.23/28,7/9,5/7,11/18