`@` `\text {Ans}`

`\downarrow`

`18*15 + 35 + 15*32 + 35*49`

`= 15 (18+32) + 35(1+49)`

`= 15*50 + 35*50`

`= 50*(15+35)`

`= 50*50`

`= 2500`

=15*50+35*50

=50*50

=2500

\(18.15+35+15.32+35.49\)

\(=18.15+35.1+15.32+35.49\)

\(=\left(15+35\right).\left(18+32+49+1\right)\)

\(=50.100\)

\(=5000\)

\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)

= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)

=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)

= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)

\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)

=  \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)

= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)

= 1 + 1 + 1 = 3

\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)

= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!

`1,`

`a,`

`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`

`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`

`= 7/19 \times (8/23 + 15/23 + 1) + 1`

`= 7/19 \times 2 + 1`

`=14/19 + 1`

`= 33/19`

`b,`

`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`

`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`

`= 0,75 + 1 + 1 + 0,25`

`= (0,75 + 0,25) + 1 + 1`

`= 1+1+1=3`

`c,`

`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`

`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)

`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).

a) \(\dfrac{3}{35}+\dfrac{7}{20}+\dfrac{32}{35}+\dfrac{13}{20}\)

Áp dụng tính chất giao hoán, kết hợp của phép cộng, ta được:

\(\left(\dfrac{3}{35}+\dfrac{32}{35}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\)

\(=1+1\)

\(=2\)

b) \(\dfrac{18\cdot15\cdot56}{42\cdot27\cdot25}=\dfrac{2\cdot3\cdot3\cdot5\cdot3\cdot4\cdot2\cdot7}{2\cdot3\cdot2\cdot2\cdot3\cdot9\cdot5\cdot5}\)

\(=\dfrac{2\cdot2\cdot3\cdot3\cdot3\cdot4\cdot5\cdot7}{2\cdot2\cdot2\cdot3\cdot3\cdot5\cdot5\cdot9}=\dfrac{3\cdot2\cdot2\cdot7}{2\cdot5\cdot9}=\dfrac{42}{45}\)

a: 29+131+237+763

=160+1000

=1160

b: 65+327+15+73

=65+15+327+73

=80+400

=480

c: \(12+54:8-8\)

=12+3-8

=15-8

=7

d: \(45\cdot58+45\cdot42\)

\(=45\cdot\left(58+42\right)\)

\(=45\cdot100=4500\)

e: \(35\cdot34+35\cdot26+40\cdot35\)

\(=35\cdot\left(34+26+40\right)\)

\(=35\cdot100=3500\)

f: \(65\cdot25+65\cdot45+30\cdot65\)

\(=65\cdot\left(25+45+30\right)\)

\(=65\cdot100=6500\)

g: \(750:\left\lbrace32-\left\lbrack2^2+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace+100\)

\(=\frac{750}{32-\left\lbrack4+5\cdot9-42\right\rbrack}+100=\frac{750}{32-4-45+42}+100\)

\(=\frac{750}{28-3}+100\)

=750:25+100

=30+100

=130

h: \(\left\lbrace630:\left\lbrack16+3\cdot\left(6+3\cdot4\right)\right\rbrack\right\rbrace-1\)

\(=\frac{630}{16+3\cdot\left(6+12\right)}-1=\frac{630}{16+3\cdot18}-1\)

\(=\frac{630}{70}-1\)

=9-1=8

i: \(5871:\left\lbrack928-\left(247-82\right)\cdot5\right\rbrack+2175^0\)

\(=\frac{5871}{928-165\cdot5}+1\)

\(=\frac{5871}{928-825}+1=\frac{5871}{103}+1=57+1=58\)

k: \(375:\left\lbrace32-\left\lbrack4+\left(5\cdot3^2-42\right)\right\rbrack\right\rbrace-14\)

\(=\frac{375}{32-\left\lbrack4+5\cdot9-42\right\rbrack}-14\)

\(=\frac{375}{32-\left\lbrack4+45-42\right\rbrack}-14=\frac{375}{32-\left(4+3\right)}-14=\frac{375}{32-7}-14\)

\(=\frac{375}{25}-14\)

=15-14

=1

áp dụng kiến thức tính nhanh ý

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275

= 1275

=1275

=1245

Có ai rảnh đâu mà đi ngồi cộng ngần đấy số ra.

mình còn ko bt cơ mà mai nộp r

mik chỉ lm đc 1 câu thôi mong bn like cho
(13911:3849−5211:3849):(4938.511)={(13+911).4938−(5+211).4938}:(4938.511)=4938.(13−5+911−211):(4938.511)=4938.(8+711):(4938.511)=(8+711):511=19

\(18.15+35+15.32+35.4+9\)

\(=\left(18.15+15.32\right)+\left(35+35.4\right)+9\)

\(=\left[15.\left(18+32\right)\right]+\left[35.\left(1+4\right)\right]+9\)

\(=\left[15.50\right]+\left[35.5\right]+9\)

\(=750+175+9\)

\(=934\)

= 454.46875

\(18.15+35+15.32+35.4+9\)

\(=15.\left(18+32\right)+35.\left(1+4\right)+9\)

\(=15.50+35.5+9\)

\(=15.50+\left(15+20\right).5+9\)

\(=15.50+15.5+20.5+9\)

\(=15.\left(50+5\right)+100+9\)

\(=15.55+109\)

\(=825+109=934\)

Bai nay la Phan so hay 2 bai riêng chu ban ghi vay ai ma biết lam the nao

\(a,\frac{-15}{32}.\left(\frac{-18}{25}\right).\left(\frac{-1}{2}\right)^2\)

\(=\frac{-15}{32}.\left(\frac{-18}{25}\right).\frac{1}{4}\)

\(=\frac{-15.\left(-18\right).1}{32.25.4}\)

\(=\frac{27}{320}\)

\(b,\frac{35}{34}.\left(\frac{-17}{39}\right).\frac{26}{45}\)

\(=\frac{35.\left(-17\right).26}{34.39.45}\)

\(=\frac{-7}{27}\)