Bài 1:

a.\(150+50:5-2.3^2\)

\(=150+50:5-2.9\)

\(=150+10-18\)

\(=160-18\)

\(=142\)

b,\(375+693+625+307\)

\(=375+625+\left(693+307\right)\)

\(=1000+1000\)

\(=2000\)

e.\(500-\left\{5\left[409-\left(2^3.3-21\right)^2\right]-1724\right\}\)

\(=500-\left\{5\left[409-\left(8.3-21\right)^2\right]-1724\right\}\)

\(=500-\left\{5\left[409-\left(24-21\right)^2\right]-1724\right\}\)

\(=500-\left\{5\left[409-3^2\right]-1724\right\}\)

\(=500-\left\{5\left[409-9\right]-1724\right\}\)

\(=500-\left\{5.400-1724\right\}\)

\(=500-\left\{2000-1724\right\}\)

\(=500-276\)

\(=224\)

d.\(2^4.5-\left[131-\left(13-4\right)^2\right]\)

\(=16.5-\left[131-11^2\right]\)

\(=80-\left[131-121\right]\)

\(=80-10\)

\(=60\)

c.\(4.2^3-3^4:3^3+25^2:5^2\)

\(=4.8-3^1+625:25\)

\(=32-3+25\)

\(=29+25\)

\(=54\)

Bài 2:

a.\(219-7\left(x+1\right)=100\)

\(7\left(x+1\right)=219-100\)

\(7\left(x+1\right)=119\)

\(x+1=119:7\)

\(x+1=17\)

\(x=17-1\)

\(x=16\)

b.(3x-6)3=36

=>3x-6=36:3

=>3x-6=12

=>3x=12+6

=>3x=18

=>x=18:3

=>x=6

c.716-(x-143)=659

=>x-143=716-659

=>x-143=57

=>x=57+143

=>x=200

d.30-[4(x-2)+15]=3

=>4(x-2)+15=30-3

=>4(x-2)+15=27

=>4(x-2)=27-15

=>4(x-2)=12

=>x-2=12:4

=>x-2=3

=>x=3+2

=>x=5

e.\(\text{[(8x-12):4]3}^3=3^6\)

=>[(8x-12):4]27=729

=>(8x-12):4=729:27

=>(8x-12):4=27

=>8x-12=27.4

=>8x-12=108

=>8x=108+12

=>8x=120

=>x=120:8

=>x=15

hãy kết bạn với tui đi

gọi số tự nhiên càn tìm là a
Ta có:  a:12 dư 5      a-5 chia hết cho 12
            a:18 dư 5 =>a-5 chia hết cho 18
            a:21 dư 5      a-5 chia hết cho21
    => a-5 thuộc BC(12,18,21)
  12=2^2 . 3      =>BCNN(12,18,21)=2^2 .3^2 .7=252
   18=2 . 3^2   =>BC(12,18,21)=B(252)=
   21=3 . 7                                                  

   =>BC(12,18,21)=B(252)=B(252)=(...-1008;-756,-504;-252;0;252;504;756,1008,...)

  Mà a nhỏ hơn 1000 và lớn hơn 700 => a =756

Vậy a=756

2 mũ x : 4 = 32

= 2^x = 32.4

= 2^x = 128

= 2^x = 2^7

= x = 7

2 mũ x : 4 = 32

32 . 4 = 2 mũ x

128 = 2 mũ x

 vì 2 mũ 7 = 128 nên 2 mũ x = 2 mũ 7

=> x = 7

7\8 - 5\6 : 15\2

= 7/8 - 5/6 x 2/15

= 7/8 - 5x 2/ 6 x15

= 7/8 - 1/9 

= 63/72 - 8/72

= 55/72

7/8 - 5/6:15/2

=7/8-5/6 x 2/15

=7/8-1/9

=55/72 

tick mình với nhé

\(\left(x\times1\right)+\left(x\times2\right)+\left(x\times3\right)+...+\left(x\times100\right)=14900\)

\(x+2x+3x+...+100x=14900\)

\(x\times5050=14900\Leftrightarrow x=14900\div5050=\dfrac{298}{101}\) 

mình cảm ơn bạn no name nha