Ta có 1x2x3x...x9-1x2x3x...x8=1x2x3x...x8x8

Mà 1x2x3x...x8x8-1x2x3x...x8x8=0 

Suy ra 1x2x3x...x9-1x2x3x...x8-1x2x3x...x8x8=0

=362880-40320-5040x8^2

=317520x8^2

=2540160^2

=6452412825600

Tk plz

:))

Thanks

=362880-40320-5040x8^2

=317520x8^2

=2540160^2

=6452412825600

\(a.-\dfrac{1}{2}\)

\(b.3\)

\(c.5\)

1.2.3...9 - 1.2.3...8 - 1.2.3...8²

= 1.2.3...8.(9 - 1 - 8)

= 1.2.3...8.0

= 0

\(a,12,3\cdot4,7+5,3\cdot12,3-1,4\cdot7,5+7,5\cdot5,4\)

\(=12,3\cdot\left(4,7+5,3\right)-7,5\cdot\left(1,4+5,4\right)\)

\(=12,3\cdot10-7,5\cdot6,8\)

\(=123-51\)

\(=72.\)

\(b,3\cdot x-1=\frac{3}{4}:\frac{15}{16}\)

\(\Leftrightarrow3\cdot x-1=\frac{3}{4}\cdot\frac{16}{15}\)

\(\Leftrightarrow3\cdot x-1=\frac{4}{5}\)

\(\Leftrightarrow3\cdot x=\frac{4}{5}+1\)

\(\Leftrightarrow3\cdot x=\frac{9}{5}\)

\(\Leftrightarrow x=\frac{9}{5}\div3\)

\(\Leftrightarrow x=\frac{9}{5}\cdot\frac{1}{3}\)

\(\Leftrightarrow x=\frac{3}{5}\)

a) \(12,3\times4,7+5,3\times12,3-1,4\times7,5+7,5\times5,4\)

\(=12,3\times\left(4,7+5,3\right)+7,5\times\left(5,4-1,4\right)\)

\(=12,3\times10+7,5\times4\)

\(=123+30\)

\(=153\)

b) \(3.x-1=\frac{3}{4}:\frac{15}{16}\)

\(\Rightarrow3.x-1=\frac{4}{5}\)

\(\Rightarrow3.x=\frac{9}{5}\Rightarrow x=\frac{3}{5}\)

dấu " \(.\) " là dấu nhân

\(\left\{\left[27.11-\left(x+12\right).8\right].3-79\right\}:5=100\)

=>\(\left[297-8.x+12.8\right].3-79=100.5\)

=> \(\left[297-8.x+96\right].3-79=500\)

=> \(\left[297-8.x+96\right].3=500+79\)

=> \(\left[\left(297+96\right)-8.x\right].3=579\)

=> \(393-8.x=579:3\)

=> \(393-8.x=193\)

=> \(8.x=393-193\)

=> \(8.x=200=>x=200:8=25\)

Vậy \(x=25\)

Chúc bạn Hk tốt!!!!

a: 12+18+24+36+42+48

=30+60+90

=90+90

=180

b: 327-16+216-27+500

=(327-27)+(216-16)+500

=300+200+500

=1000

c: \(385\cdot485+386\cdot515\)

\(=385\cdot485+385\cdot515+515\)

\(=385\cdot1000+515=385000+515=385515\)

d: \(16\cdot48+8\cdot48+16\cdot28\)

\(=16\cdot\left(48+28\right)+8\cdot2\cdot24\)

\(=16\cdot\left(76+24\right)=16\cdot100=1600\)

e: \(2\cdot4\cdot8\cdot50\cdot25\cdot125=4\cdot25\cdot8\cdot125\cdot2\cdot50\)

\(=100\cdot100\cdot1000=10000000\)

g: \(17\cdot8+51\cdot4=17\cdot4\cdot\left(2+3\right)=17\cdot4\cdot5=17\cdot20=340\)

1x2x3x..x9-1x2x3x..x8-1x2x3x..x82

(3x4x216)2 / 11x213 x411 -169

13-12+11+10-9+8-7-6+5-4+3+2-1

A=666..66(100 chữ số 6)x999..99(100 chữ số 9)

Mình cần gấp giúp mình nha!

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