\(=\dfrac{17}{23}\cdot\dfrac{23}{17}\cdot\dfrac{1}{2}\cdot\dfrac{3}{4}\cdot\left(-80\right)=-80\cdot\dfrac{3}{8}=-30\)
\(=\dfrac{17}{23}\cdot\dfrac{23}{17}\cdot\dfrac{1}{2}\cdot\dfrac{3}{4}\cdot\left(-80\right)=-80\cdot\dfrac{3}{8}=-30\)
-8/15.3/7.15/-8.14=..... 17/27.13/9-4/9.17/27=.......
Nhân các phân số (chú ý rút gọn nếu có thể)
a) \(\dfrac{-1}{4}.\dfrac{1}{3}\)
b) \(\dfrac{-2}{5}.\dfrac{5}{-9}\)
c) \(\dfrac{-3}{4}.\dfrac{16}{17}\)
d) \(\dfrac{-8}{3}.\dfrac{15}{24}\)
e) \(\left(-5\right).\dfrac{8}{15}\)
g) \(\dfrac{-9}{11}.\dfrac{5}{18}\)
1/2+1/3+1/4+......+1/15=a/b, chứng minh a không chia hết cho 17
Tính theo cách hợp lí:
a) (68 - 8) . 14 + (-27 - 33) . 15
b) 37 . (55 - 49) - 49 . (55 - 37)
c) (-4) . 19 . (-8) . (-25) . (125)
d) 32 . (-125) . 17 . (-25)
Tính :
a) \(\dfrac{2}{3}+\dfrac{1}{5}.\dfrac{10}{7}\)
b) \(\dfrac{7}{12}-\dfrac{27}{7}.\dfrac{1}{18}\)
c) \(\left(\dfrac{23}{41}-\dfrac{15}{82}\right).\dfrac{41}{25}\)
d) \(\left(\dfrac{4}{5}+\dfrac{1}{2}\right).\left(\dfrac{3}{13}-\dfrac{8}{13}\right)\)
a) \(\dfrac{-21}{15}\).\(\dfrac{-10}{14}\) b)\(\left(-\dfrac{2}{3}\right)^2\) c)\(\dfrac{-3}{4}\).\(\dfrac{-4}{5}\).\(\dfrac{16}{9}\) d)\(\dfrac{-8}{3}\).\(\dfrac{5}{6}\) e)\(\dfrac{16}{30}\).\(\dfrac{5}{12}\) f) \(\dfrac{13}{30}\).\(\dfrac{-1}{5}\) g)\(\dfrac{2}{21}\).\(\dfrac{3}{28}\) h)\(\left(\dfrac{-3}{4}\right)^3\)
Bài 1 Tìm số nguyên x biếtrằng tổng của ba số x, -1 và 9 bằng 23
Tính các tích sau:
A=3/4 . 8/9 .15/16 . ..... . 9999/10000
B=(1 - 1/4)(1 - 1/9). ..... . (1 - 1/10000)
C=(1 + 1/1.3)(1 + 1/2.4)(1 + 1/3.15). ..... .(1 + 1/99.100)
Nhanh giùm mình nha mai thi rồi.
A=3/4×8/9×15/16.......×899/900