\(\dfrac{-8}{15}.\dfrac{3}{7}.\dfrac{15}{-8}.14=\left(\dfrac{-8}{15}.\dfrac{15}{-8}\right).\left(\dfrac{3}{7}.14\right)=1.6=6\)
\(\dfrac{17}{27}.\dfrac{13}{9}-\dfrac{4}{9}.\dfrac{17}{27}=\dfrac{17}{27}.\left(\dfrac{13}{9}-\dfrac{4}{9}\right)=\dfrac{17}{27}.1=\dfrac{17}{27}\)
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)
17/23 . 8/16 . 23/17 . (-80) . 3/4
Tính một cách hợp lý:
a\(\left(\dfrac{1}{2}-1\right)\left(\dfrac{1}{3}-1\right)...\left(\dfrac{1}{100}-1\right)\)) \(x:\dfrac{99}{100}:\dfrac{98}{99}:...:\dfrac{2}{3}:\dfrac{1}{2}\)
b) \(\dfrac{5-\dfrac{5}{3}+\dfrac{5}{9}-\dfrac{5}{27}}{8-\dfrac{8}{3}+\dfrac{8}{9}-\dfrac{8}{27}}:\dfrac{15-\dfrac{15}{11}+\dfrac{15}{121}}{16-\dfrac{16}{11}+\dfrac{16}{121}}\)
c) \(\dfrac{\dfrac{1}{9}-\dfrac{5}{6}-4}{\dfrac{7}{12}-\dfrac{1}{36}-10}\)
d) \(\left(\dfrac{1}{2}+1\right)\left(\dfrac{1}{3}+1\right)...\left(\dfrac{1}{99}+1\right)\)
e)
1+2+3+4+5+6+7+8+9+0+1+2+3+4+5+6+7+8+9+9+8+7+6+5+4+3+2+1+1+34+4+6+7+8+97+6+4+3+32+4+57+7+8+8+6+65+4+3+3+46+7+8+7+64+3+3+5+68+8+6+3+3+5+78+8+6+54+5+7+8+852+3+5+89+8+5+45+7×9×9×9×9×9×9×9×9×9×9×9×8×8×7×9×9×7×7×87×7×8×7×7×8×7×7×8
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) \(\dfrac{-9}{11}.\dfrac{5}{18}\)
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)
5/6+6 và 5/6.(11 và 5/20-9 và 1/4):8 và 1/3
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)\(\left(\dfrac{-3}{4}\right)^3\)
Nhanh giùm mình nha mai thi rồi.
A=3/4×8/9×15/16.......×899/900
