\(\text{35 + (–47) – |–12|}\)

\(=-12-12\)

\(=-24\)

\(\text{(–15) – 70 : (–14) + (–32) . (–2)}\)

\(=-15+5+64\)

\(=-10+64\)

\(=54\)

\(\text{ 15 – 12 . (-3)^2 – 135 : |–15|}\)

\(=15-12.9-135:15\)

\(=15-108-9\)

\(=-102\)

Tính hợp lý:

\(\text{ –24 . 78 + 24(–35) – 24(–13)}\)

\(=24.\left(-78+\left(-35\right)-\left(-13\right)\right)\)

\(=24.\left(-100\right)\)

\(=-2400\)

học tốt

\(\frac{17}{8}+\frac{28}{15}-\frac{8}{15}=\frac{17}{8}+\frac{4}{3}=\frac{83}{24}=3\frac{11}{24}\)

=> chọn a

Đáp án : a) 311/24

\(\frac{1}{9\cdot10}+\frac{2}{10\cdot12}+\frac{3}{12\cdot15}+\frac{4}{15\cdot19}+\frac{5}{19\cdot24}+\frac{6}{24\cdot30} \)
\(=\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{12}+\frac{1}{12}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}+\frac{1}{19}-\frac{1}{24}+\frac{1}{24}-\frac{1}{30}\)
\(=\frac{1}{9}-\frac{1}{30}\)
\(=\frac{10}{90}-\frac{3}{90}\)
\(=\frac{7}{90}\)
 

\(\frac{15}{24}-\frac{2}{15}=\frac{5}{8}-\frac{2}{15}=\frac{75}{120}-\frac{16}{120}=\frac{59}{120}\)

đọc mà phát choáng

Trl

A . = 100

B = 70

C = 52

D = 22

_Hc tốt

TL:

  A=100

 B=70

C=52

D=22

tra loi 

a.100

b. 70

c.52

d.22

Ư(-24) = {-24,-12,-8,-6,-4,-3,-2,-1,1,2,3,4,6,8,12,24}

B(-24) = {0.+-24,+-48,...}

ƯC(-15,20) = {1,5,-1,-5}

\(=\dfrac{-16}{5}\cdot\dfrac{-15}{64}+\left(\dfrac{4}{5}-2-\dfrac{4}{15}\right):\dfrac{47}{24}\)

\(=\dfrac{3}{4}-\dfrac{22}{15}\cdot\dfrac{24}{47}=\dfrac{1}{940}\)