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a) \(\dfrac{11\cdot8-11\cdot3}{17-6}\)
\(=\dfrac{11\cdot\left(8-3\right)}{11}=5\)
b) \(\dfrac{24-12\cdot13}{12+4\cdot9}\)
\(=\dfrac{12\cdot\left(2-13\right)}{12\left(1+3\right)}=\dfrac{-11}{4}\)
\(\frac{3.7.8.13}{14\cdot15\cdot26}=\frac{3\cdot7\cdot8\cdot13}{2\cdot7\cdot3\cdot5\cdot2\cdot13}=\frac{8}{5\cdot2\cdot2}=\frac{8}{20}=\frac{2}{5}\)
\(\frac{3.7.8.13}{14.15.26}=\frac{3.7.2^3.13}{2.7.3.5.13.2}=\frac{1.7.2.1}{1.1.1.5.1.1}=\frac{14}{5}\)
\(\frac{11.8-11.3}{17-6}=\frac{11.\left(8-3\right)}{11}=\frac{11.5}{11}=\frac{1.5}{1}=\frac{5}{1}=5\)
\(\frac{-17.13+17.2}{11.2-11.9}=\frac{-17.13+\left(-17\right).2}{11.\left(2-9\right)}=\frac{-17.\left(-13+2\right)}{11.\left(-7\right)}=\frac{-17.\left(-11\right)}{11.\left(-7\right)}=\frac{-17.\left(-1\right)}{-1.\left(-7\right)}=\frac{17}{7}\)
\(\frac{7}{9.10^2-2.10^2}=\frac{7}{100\left(9-2\right)}=\frac{7}{100.7}=\frac{7}{700}=\frac{1}{100}\)
mình làm được tới đó thôi, hihi.
\(\dfrac{-33}{88}=\dfrac{-3}{8};11.8-\dfrac{11.3}{17-6}=88-\dfrac{33}{11}=88-3=85.\)
Bài 14 :
a. 55/66 = 55 : 11/66 : 11 = 5/6 b. -33/88 = -33 : 11/88 : 11 = -3/8 c. 2020/8080 = 2020 : 2020/8080 : 2020 = 1/4
d. 2121/-4242 = 2121 : (-101)/(-4242) : (-101) = 21/42 = 1/2
e. 130130/-260260 = 130130 : (-1001)/(-260260) : ( -1001 ) = -130/260 = -1/2
f. 1616/-1313 = 1616 : (-101)/(-1313) : (-101 ) = -16/13
Chúc bạn học tốt nha !
Bài 14 khá đơn giản nên mình sẽ bỏ qua, bạn tự làm đc mà xD
15. a) \(\frac{13\cdot9-13\cdot2}{25-12}=\frac{13\left(9-2\right)̸}{13}=7\)
b) \(\frac{42-14\cdot8}{7+21\cdot3}=\frac{14\cdot3-14\cdot8}{7+63}=\frac{14\left(3-8\right)}{70}=\frac{14\cdot\left(-5\right)}{70}=\frac{-70}{70}=-1\)
c) \(\frac{9\cdot6-18\cdot4}{12\cdot3}=\frac{\left(9\cdot2\right)\cdot\left(6:2\right)-18\cdot4}{36}=\frac{18\cdot3-18\cdot4}{36}=\frac{18\left(3-4\right)}{36}=\frac{-18}{36}=\frac{-1}{2}\)
d) \(\frac{5\cdot5^2}{9\cdot10^2-4\cdot10^2}=\frac{5\cdot5^2}{10^2\left(9-4\right)}=\frac{5\cdot5^2}{10^2\cdot5}=\frac{1}{2^2}=\frac{1}{4}\)
e) \(\frac{\left(-7\right)\cdot3-4\cdot\left(-6\right)}{\left(-5\right)\cdot3-2\cdot3}=\frac{-21+24}{-15-6}=\frac{3}{-21}=\frac{-1}{7}\)
f) \(\frac{\left(-17\right)\cdot13+17\cdot2}{-11\cdot2-11\cdot19}=\frac{-\left[17\cdot\left(13+2\right)\right]}{-\left[11\cdot\left(2-19\right)\right]}=\frac{-17\cdot13-\left(-17\right)\cdot2}{-11\cdot2+\left(-11\right)\cdot19}=\frac{-17\left(13-2\right)}{-11\left(2+19\right)}=\frac{-17\cdot11}{-11\cdot19}=\frac{-17}{-19}=\frac{17}{19}\)
* Hơi dài xD , mong bạn thông cảm *
RÚT GỌN VỀ PHÂN SỐ TỐI GIẢN
câu a) \(\dfrac{-147}{252}=\dfrac{-7}{12}\)
câu b) \(\dfrac{765}{900}=\dfrac{17}{20}\)
câu c) \(\dfrac{11\cdot3-11\cdot8}{17-6}=\dfrac{-5}{1}\)
câu d) \(\dfrac{3^5\times2^4}{8\times3^6}=\dfrac{2}{3}\)
câu e) \(\dfrac{84\cdot45}{49\cdot54}=\dfrac{10}{7}\)
a) \(\frac{17}{23}.\frac{18}{16}.\frac{23}{17}-\left(-80\right)-\frac{3}{4}\)
= \(\frac{17.18.23}{23.16.17}+80-\frac{3}{4}\)
= \(\frac{9}{8}+80-\frac{3}{4}\)
= \(\frac{3}{8}+80=\frac{643}{8}\)
b) \(\frac{5}{11}.\frac{18}{29}-\frac{5}{11}.\frac{8}{29}+\frac{5}{11}.\frac{19}{29}\)
= \(\frac{5}{11}.\left(\frac{18}{29}-\frac{8}{29}+\frac{19}{29}\right)\)
= \(\frac{5}{11}.1=\frac{5}{11}\)
c) \(\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right).\left(\frac{1}{3}+\frac{1}{4}-\frac{7}{12}\right)\)
= \(\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right).0\)
= \(0\)
a) 5
b) − 11 4
c) 2 3
d) 1 100
e) 5
f) 1