b) \(\dfrac{6\cdot9-2\cdot17}{63\cdot3-119}\)

\(=\dfrac{2\left(3\cdot9-17\right)}{7\cdot\left(3\cdot9-17\right)}\)

\(=\dfrac{2}{7}\)

a, \(\dfrac{25.13}{26.35}=\dfrac{5.1}{2.7}=\dfrac{5}{14}.\)

b, \(\dfrac{6.9-2.17}{63.3-119}=\dfrac{2.3.9-2.17}{9.7.3-17.7}=\dfrac{2\left(3.9-17\right)}{7\left(9.3-17\right)}=\dfrac{2}{7}.\)

c, \(\dfrac{3.13-13.18}{15.40-80}=\dfrac{13\left(3-18\right)}{15.40-40.2}=\dfrac{13.\left(-15\right)}{40\left(15-2\right)}=\dfrac{13.\left(-15\right)}{40.13}=\dfrac{-15}{40}=\dfrac{-3}{8}.\)d, \(\dfrac{2929-101}{2.1919+404}=\dfrac{29.101-101.1}{2.19.101+101.4}=\dfrac{101\left(29-1\right)}{38.101+101.4}=\dfrac{101\left(29-1\right)}{101\left(38+4\right)}=\dfrac{29-1}{38+4}=\dfrac{28}{42}=\dfrac{2}{3}.\)

(còn tiếp!!!)

~ Chúc bn học tốt!!! ~

a, \(-\dfrac{315}{540}\) = \(\dfrac{-315:45}{540:45}\) = \(\dfrac{-7}{12}\)        b,   \(\dfrac{25.13}{26.35}\) = \(\dfrac{25.13:5:13}{26.35:13:5}\) = \(\dfrac{5}{14}\)

c,     \(\dfrac{6.9-2.17}{63.3-119}\) = \(\dfrac{2.3.9-2.17}{7.9.3-7.17}\) = \(\dfrac{2.(27-17)}{7.(7-17)}\) = \(\dfrac{2}{7}\)

d, \(\dfrac{3.13-13.18}{15.40-80}\) = \(\dfrac{3.13(1-6)}{40.(15-2)}\) = \(\dfrac{-3.13.5}{40.13}\) = \(\dfrac{-15}{40}\) = \(\dfrac{-15:5}{40:5}\) = \(-\dfrac{3}{8}\)

2.3+4.6+14.21/3.5+6.10+21.35

= 2 . 3 + 2 . 2 . 3 . 2 + 7 .

\(\frac{2\cdot3+4\cdot6+14\cdot21}{3\cdot5+6\cdot10+21\cdot35}\)=\(\frac{2\cdot3\cdot\left(1+2\cdot2+7\cdot7\right)}{3\cdot5\cdot\left(1+2\cdot2+7\cdot7\right)}\)

Sau đó ta chia tử và mẫu cho (1+2*2+7*7) thì ta có phân số

\(\frac{2\cdot3}{3\cdot5}\)=\(\frac{2}{5}\)(rút gọn tử và mẫu cho 3)

..............

\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}=\frac{2.3+8.3+98.3}{3.5+3.20+3.45}=\frac{3.\left(2+8+98\right)}{3.\left(5+20+45\right)}=\frac{108}{70}=\frac{54}{35}=1\frac{19}{35}\)

rút gọn PS

3.7.13.37.39-10101/505050-70707

làm bài dưới :

rút gọn phân số : 

\(\frac{3.7.13.37.39-10101}{505050-70707}\)

\(=\frac{10101.39-10101}{50.10101-7.10101}\)

\(=\frac{10101.\left(39-1\right)}{10101.\left(50-7\right)}\)

\(=\frac{38}{43}\)

a)\(\dfrac{6.9-2\cdot17}{63\cdot3-119}=\dfrac{2\cdot3\cdot9-2\cdot17}{7\cdot9\cdot3-7\cdot17}=\dfrac{2\cdot27-2\cdot17}{7\cdot27-7\cdot17}=\dfrac{2\left(27-17\right)}{7\left(27-17\right)}=\dfrac{2}{7}\)

b) \(\dfrac{3\cdot13-13\cdot18}{15\cdot40-80}=\dfrac{13\cdot\left(3-18\right)}{\left(15-2\right)\cdot40}=\dfrac{13\cdot\left(-15\right)}{13\cdot40}=-\dfrac{15}{40}=-\dfrac{3}{8}\)

c) \(\dfrac{25\cdot13}{26\cdot35}=\dfrac{5^2\cdot13}{2\cdot13\cdot5\cdot7}=\dfrac{5}{14}\)

a) \(\dfrac{6.9-2.17}{63.3-119}=\dfrac{2.3.9-2.17}{7.9.3-17.7}=\dfrac{2.\left(3.9-17\right)}{7.\left(9.3-17\right)}=\dfrac{2}{7}\)

b)\(\dfrac{3.13-13.18}{15.40-80}=\dfrac{3.13-13.18}{15.40-40.2}=\dfrac{13.\left(3-18\right)}{40.\left(15-2\right)}=\dfrac{13.\left(-15\right)}{40.13}=\dfrac{-15}{40}=\dfrac{-3}{8}\)

c) \(\dfrac{25.13}{26.35}=\dfrac{5.5.13}{13.2.5.7}=\dfrac{5}{2.7}=\dfrac{5}{14}\)

\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}=\frac{2.3+4.6+2.7.3.7}{3.5+2.3.5.2+3.7.5.7}\)

\(=\frac{6.1+4.6+6.49}{15.1+15.4+15.49}\)

\(=\frac{6\left(1+4+49\right)}{35\left(1+4+49\right)}=\frac{6}{35}\)

tren tu : dat 2.3 ra ngoai

trong ngoặc: 1+2.2+7.7

dưới mẫu : dat 3.5 ra ngoai

trong ngoặc: 1+2.2+7.7

rút gọn: 2.3/3.5=2/5

cho mk vs