\(\left[230-\left(15-5x\right)\right].3=390\\\Rightarrow 230-\left(15-5x\right)=130\\ \Rightarrow15-5x=100\\ \Rightarrow5x=-85\\ \Rightarrow x=-17\)

128 - 3 ( x + 4 ) = 23

         3 ( x + 4 ) = 128 - 23

         3 ( x + 4 ) = 105

              x + 4   = 105 : 5

              x + 4   = 35

              x         = 35 - 4

              x         = 31

128 - 3 ( x + 4 ) = 23

         3 ( x + 4 ) = 128 - 23

         3 ( x + 4 ) = 105

              x + 4   = 105 : 5

              x + 4   = 35

              x         = 35 - 4

              x         = 31

k mik nha

5 lấy đâu ra vậy Bùi Đình Hải?

720 : [41-(2x-5)] =2^3 . 5

<=> 41-(2x-5)=720:40=18

<=> 2x-5=41-18=23

<=>2x=23+5=28

<=> x=28:2=14

2^x-15=17

<=> 2^x=17+15=32

<=> 2^x=2^5

<=> x=5

(7x-11)^3= 2^5.5^2+200

<=> (7x-11)^3=1000

<=> (7x-11)^3=10^3

<=> 7x-11=10

<=> 7x=10+11=21

<=> x=21:7=3

2^x-15=17 nhe. Minh viet nham

\(\left(x+15\right)-125=5^7:5^5\)

\(\Rightarrow\left(x+15\right)-125=5^2\)

\(\Rightarrow\left(x+15\right)-125=25\)

\(\Rightarrow x+15=25+125\)

=> x+15=150

=> x=150-15

Vậy x=135.

\(720:\left[41-\left(2x-5\right)\right]=2^3.5\)

=> 720:[41-(2x-5)]=8.5

=> 720:[41-(2x-5)]=40

=> 41-(2x-5)=720:40

=> 41-(2x-5)=18

=> 2x-5=41-18

=> 2x-5=23

=> 2x=23+5

=> 2x=28

=> x=28:2

Vậy x=14.

\(2^7-3.\left(x+4\right)=23\)

=> 128-3.(x+4)=23

=> 3.(x+4)=128-23

=> 3.(x+4)=105

=> x+4=105:3

=> x+4=35

=> x=35-4

Vậy x=31.

\(2015^x.5^3=125\)

=> 2015^x.5³=5³

=> 2015^x=5³:5³

=> 2015^x=1

=> 2015^x=2015⁰

Vậy x=0.

720:[41-(2x-5)]=2^3.5

720:[41-2x+5]=40

[41+5-2x]=720:40

46-2x=18

2x=46-18

2x=28

x=14

a,  2^x.4=128

2^x=128:4

2^x=32

2^x=2⁵

x=5

Vay x=5

b, x¹⁵=x

x=1

Vay x=1

a: \(\left[\left(10-x\right)\cdot2+51\right]:3-2=3\)

=>\(\left[2\left(10-x\right)+51\right]:3=5\)

=>\(\left[2\left(10-x\right)+51\right]=15\)

=>\(2\left(10-x\right)=15-51=-36\)

=>10-x=-36/2=-18

=>\(x=10-\left(-18\right)=10+18=28\)

b: \(\left(x-12\right)-15=20-\left(17+x\right)\)

=>\(x-12-15=20-17-x\)

=>\(x-27=3-x\)

=>\(2x=30\)

=>\(x=\dfrac{30}{2}=15\)

c: \(720-\left[41-\left(2x-5\right)\right]=2^3\cdot5\)

=>\(720-\left[41-2x+5\right]=8\cdot5=40\)

=>\(\left[41-2x+5\right]=720-40=680\)

=>-2x+46=680

=>-2x=680-46=634

=>\(x=\dfrac{634}{-2}=-317\)

\(71+\left(26-3x\right)\div5=75\)

\(\left(26-3x\right)\div5=4\)

\(26-3x=20\)

\(3x=6\Leftrightarrow x=2\)

\(20-\left[7\left(x-3\right)+4\right]=2\)

\(7x-21+4=18\)

\(7x-17=18\)

\(7x=25\Leftrightarrow x=\frac{25}{7}\)

\(3^x.2+15=33\)

\(3^x.2=18\)

\(3^x=9\Leftrightarrow x=2\)

1: \(\dfrac{2x^3+11x^2+18x-3}{2x+3}\)

\(=\dfrac{2x^3+3x^2+8x^2+12x+6x+9-12}{2x+3}\)

\(=x^2+4x+3-\dfrac{12}{2x+3}\)