bấm máy tính

tự vận đông đê

a) 12/38

b) 44/18

\(a,-\left|-13\right|+23=-13+23=10\)

b, \(80-\left[130-\left(12-4\right)^2\right]\)

\(=80-\left[130-8^2\right]\)

= \(80-66=14\)

c, \(23-\left(12-4\right)^2+\left|15\right|\)

= \(23-8^2+15\)

= \(23-64+15=-26\)

Tính:

a) (-23) + 46 + (-17) +14

= (46 + 14) - (23 + 17)= 60 - 40

= 20 

b) (-3-21) : 4

= - 24 : 4

= - 6

a) Ta có: (-23)+46+(-17)+14

=(-23-17)+(46+14)

=-40+60

=20

b) Ta có: (-3-21):4

=-24:4

=-6

mik làm lun nhé ko ghi lại đề bài

a, =-(23+17)+(46+14)

=-40+60

=20

b, =-24:4

=-6

\(A=98.42-\left\{50.\left[\left(18-2^3\right):2+3^2\right]\right\}\)

\(=98.42-\left\{50.\left[\left(18-8\right):2+9\right]\right\}\)

\(=98.42-\left[50\left(10:2+9\right)\right]\)

\(=98.42-\left(50.14\right)\)

\(=4116-700=3416\)

\(B=-80-\left[-130-\left(12-4\right)^2\right]+2008^0\)

\(=-80-\left(-130-8^2\right)+1\)

\(=-80-\left(-130-64\right)+1\)

\(=-80+130+64+1\)

\(=115\)

\(C=1024:2^4+140:\left(38+2^5\right)-7^{23}:7^{21}\)

\(=1024:16+140:\left(38+32\right)-7^2\)

\(=64+140:70-49\)

\(=64+2-49=17\)

\(D=\left(2^{17}+15^4\right).\left(3^{19}-2^{17}\right).\left(2^4-4^2\right)\)

\(=\left(2^{17}+15^4\right).\left(3^{19}-2^{17}\right).\left(16-16\right)\)

\(=\left(2^{17}+15^4\right).\left(3^{19}-2^{17}\right).0\)

\(=0\)

\(E=100+98+96+....+4+2-97-95-....-3-1\)

\(=100+\left(98-97\right)+\left(96-95\right)+.....+\left(2-1\right)+\left(1-0\right)\)

\(=100+1+1+...+1+1\)

Vì lập được 49 cặp nên sẽ có 49 số 1

\(\Rightarrow E=100+1.49=100+49=149\)

a: Số số hạng là 100-50+1=51 số

Tổng là (100+50)*51/2=51*75=3825

b: Số số hạng là (223-21):2+1=102(số)

Tổng là (223+21)*102/2=12444

c: Số số hạng là (72-12):4+1=16(số)

Tổng là (72+12)*16/2=672

d: Số số hạng là (124-4):6+1=21(số)

Tổng là (124+4)*21/2=1344

Bài 3:

a: Ta có: \(23\left(42-x\right)=23\)

\(\Leftrightarrow42-x=1\)

hay x=41

b: Ta có: 15(x-3)=30

nên x-3=2

hay x=5

Bài 1: 

a: 32+89+68=100+89=189

b: 64+112+236=300+112=412

c: \(1350+360+650+40=2000+400=2400\)

Bài 1:

a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\)  + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)

=  \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)

= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)

= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)

= 0 + 1 - \(\dfrac{5}{8}\)

= \(\dfrac{3}{8}\)

b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))

= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)

= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)

= 0 + 0 + 0 - \(\dfrac{7}{5}\)

= - \(\dfrac{7}{5}\)

Bài 1 c;

   \(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))

=  \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)

= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)

= 0 + 0 - 1 + \(\dfrac{80}{87}\)

= - \(\dfrac{7}{87}\)

Bài 1 d; 

   \(\dfrac{1}{25}\) - \(\dfrac{4}{27}\) + (-\(\dfrac{23}{27}\) + \(\dfrac{-1}{25}\) - \(\dfrac{5}{43}\)) + \(\dfrac{5}{43}\) - \(\dfrac{4}{7}\)

= \(\dfrac{1}{25}\) - \(\dfrac{4}{27}\) - \(\dfrac{23}{27}\) - \(\dfrac{1}{25}\) - \(\dfrac{5}{43}\) + \(\dfrac{5}{43}\) - \(\dfrac{4}{7}\)

= (\(\dfrac{1}{25}\) - \(\dfrac{1}{25}\)) - (\(\dfrac{4}{27}\) + \(\dfrac{23}{27}\)) - (\(\dfrac{5}{43}\) - \(\dfrac{5}{43}\)) - \(\dfrac{4}{7}\)

= 0 - 1 - 0 - \(\dfrac{4}{7}\)

= \(\dfrac{-11}{7}\)

a) \(17+188+183=205+183=388\)

b) \(80-\left[130-\left(12-4\right)^2\right]\)

\(=80-\left(130-64\right)\)

\(80-66=14\)

c) \(2^3.17-2^3.14\)

\(8.17-8.14\)

\(=8.\left(17-14\right)\)

\(=8.3=24\)