a)  2345 − 1000 : [19-2(21-18) 2 ]=2345-1000:1=1345

b)  205 − [ 1200 − ( 4 2 − 2.3 ) 3 ]=205-( 1200 − 1000 ) = 5

a: \(\left(\frac{9}{25}-2,18\right):\left(3\frac45+0,2\right)\)

=(0,36-2,18):(3,8+0,2)

=-1,82:4

=-0,455

b: \(\frac38\cdot19\frac13-\frac38\cdot33\frac13\)

\(=\frac38\cdot\left(19+\frac13-33-\frac13\right)\)

\(=\frac38\cdot\left(-14\right)=-\frac{42}{8}=-\frac{21}{4}\)

c: \(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\)

\(=\left(1+\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5\)

=1+1+0,5

=2,5

d: Sửa đề: \(\frac{2^{12}\cdot3^5-4^6\cdot81}{2^{12}\cdot3^6+8^4\cdot3^5}\)

\(=\frac{2^{12}\cdot3^5-2^{12}\cdot3^4}{2^{12}\cdot3^6+2^{12}\cdot3^5}=\frac{2^{12}\cdot3^4\cdot\left(3-1\right)}{2^{12}\cdot3^5\cdot\left(3+1\right)}=\frac13\cdot\frac24=\frac13\cdot\frac12=\frac16\)

e: \(4\cdot\left(-\frac12\right)^2-2\cdot\left(-\frac12\right)^2+3\cdot\left(-\frac12\right)+1\)

\(=2\cdot\frac14-\frac32+1\)

=1/2-3/2+1

=-2/2+1

=-1+1

=0

g: \(\sqrt{\frac{4}{81}}:\sqrt{\frac{25}{81}}-1\frac25\)

\(=\frac29:\frac59-\frac75=\frac25-\frac75\)

=-5/5

=-1

1) \(100-\left(3.5^2-2.3^2\right)\)

\(=100-\left(3.25-2.9\right)\)

\(=100-\left(75-18\right)\)

\(=100-57\)

\(=43\)

2) \(2665:\left[213-\left(17-3^2\right)\right]+347.5^2\)

\(=2665:\left[213-\left(17-9\right)\right]+347.25\)

\(=2665:\left[213-8\right]+8675\)

\(=2665:205+8675\)

\(=13+8675\)

\(=8688\)

a, 100 - ( 3. 5² - 2 . 3² )

= 100 - 3.( 5² - 6 )

= 100 - 3 .19

= 100 - 57

=43

b, 2665: [ 213 - ( 17 - 3² ) ] + 347 . 5²

= 2665 : [213 - 8 ] + 8675

= 13 + 8675

=8688

1,100-(3.5\(^2\)-2.3\(^2\))

=100-(3.25-2.9)

=100-(75-18)

=100-57

=43

2,2665:\([\)213-(17-3\(^2\))\(]\)+347.5\(^2\)

=2665:\([\)213-8\(]\)+8675

=2665:205+8675

=13+8675

=8688

   ^{\(75.17-17.25+5^2\)}

 \(=75.17-17.25+25\)

 \(=17.\left(75-25+25\right)\)

  \(=17.\left(50+25\right)\)

  \(=17.75\)

  \(=1275\)

75x17-17x25+5²

=17x(75-25)+5²

=17x50+5²

=850+25

=875

bài này dễ mà bạn bạn chỉ cần đổi ra rồi tính bình thường là đc mà

Bài 1:

\(A=2^2\cdot3-4\\ =4\cdot3-4\\ =4\cdot\left(3-1\right)\\ =4\cdot2\\ =8\\ B=16-2^3\cdot2\\ =16-16\\ =0\\ C=4^2-4\cdot2\\ =4\cdot\left(4-2\right)\\ =4\cdot2\\ =8\\ D=3^3-3\cdot3^2\\ =3^3-3^3\\ =0\)

a) 81^11.3^17/27^10.9^15

=(9^2)^11.3^17/(3^3)^10.9^15

=3^44.3^17/3^30.3^30

=3^61/3^60

=3

b) A =( (2^12.3^5 - 2^12.3^4)/ (2^12.3^6 + 2^12.3^5) ) - ((5^10.7^3 - 5^10.7^4)/(5^9.7^3 + 5^9.2^3.7^3))

=(2^12.3^4(3-1))/2^12.3^5(3+1) - 5^10.7^3(1-7)/5^9.7^3(1+8)

=2/12- (-30/9)=1/6 + 10/3 = 7/2

3/6, /8,4/6

a) 1-3+5-7+9-12+15-18

= (1+ 9) - (3+7) + (5+15) - (12+18) 

= 10 - 10 + 20 - 30 = -10.

b) (-2)+5-7+9-11+13-15+19-21

= 5 - 11 - 2 -2 = 5 - (11+2+2)

= 5 - 15 = -10 

Bài 1: 

a) Ta có: 1-3+5-7+9-12+15-18

=(1+9)-(3+7)+(5+15)-(12+18)

=10-10+20-30

=-10

b) Ta có: \(\left(-2\right)+5-7+9-11+13-15+19-21\)

\(=3+2+2+4-21\)

\(=5+6-21\)

=11-21=-10