a ) \(\left(3x^2-4x+5\right)\left(2x^2-4\right)-2x\left(3x^3-4x^2+8\right)\)

\(=\left(3x^2-4x+5\right).2x^2-4\left(3x^2-4x+5\right)-6x^4+8x^3-16x\)

\(=6x^4-8x^3+10x^2-12x^2+16x-20-6x^4+8x^3-16x\)

\(=\left(6x^4-6x^4\right)+\left(8x^3-8x^3\right)-\left(12x^2-10x^2\right)+\left(16x-16x\right)-20\)

\(=-2x^2-20\)

b ) \(\left(1-3x+x^2\right)\left(2-4x\right)+2x\left(2x^2+5\right)\)

\(=2\left(1-3x+x^2\right)-4x\left(1-3x+x^2\right)+4x^3+10x\)

\(=2-6x+2x^2-4x+12x^2-4x^3+4x^3+10x\)

\(=\left(4x^3-4x^3\right)+\left(12x^2+2x^2\right)+\left(10x-6x-4x\right)+2\)

\(=14x^2+2\)

ta có 5^x+5^x*25=650 suy ra 5^x *26=650 ,5^x=25 suy ra x=2

Mk giúp phần đầu nhé!

Có 5^x+5^x+2=650

=> 5^x.(1+5²)=650

     5^x. 26=650

     5^x=650:26

     5^x=25

=> x=2

12*34=1*68

=>12*34-6*68=0=>bieu thuc = 0

Ít thôi -..-

a) ( 3x + 2 )( 2x + 9 )  - ( x + 3 )( 6x + 1 ) = ( x + 1 )² - ( x + 2 )( x - 2 )

<=> 6x² + 31x + 18 - ( 6x² + 19x + 3 ) = x² + 2x + 1 - ( x² - 4 )

<=> 6x² + 31x + 18 - 6x² - 19x - 3 = x² + 2x + 1 - x² + 4

<=> 12x + 15 = 2x + 5

<=> 12x - 2x = 5 - 15

<=> 10x = -10

<=> x = -1

b) ( 2x + 3 )( x - 4 ) + ( x - 5 )( x - 2 ) = ( 3x - 5 )( x - 4 )

<=> 2x² - 5x - 12 + x² - 7x + 10 = 3x² - 17x + 20

<=> 3x² - 12x - 2 = 3x² - 17x + 20

<=> 3x² - 12x - 3x² + 17x = 20 + 2

<=> 5x = 22

<=> x = 22/5

c) ( x + 2 )³ - ( x - 2 )³ - 12x( x - 1 ) = -8

<=> x³ + 6x² + 12x + 8 - ( x³ - 6x² + 12x - 8 ) - 12x² + 12x = -8

<=>  x³ + 6x² + 12x + 8 - x³ + 6x² - 12x + 8 - 12x² + 12x = -8

<=> 12x + 16 = -8

<=> 12x = -24

<=> x = -2

d) ( 3x - 1 )² - 5( x + 1 ) + 6x - 3.2x + 1 - ( x - 1 )² = 16

<=> 9x² - 6x + 1 - 5x - 5 + 6x - 6x + 1 - ( x² - 2x + 1 ) = 16

<=> 9x² - 11x - 3 - x² + 2x - 1 = 16

<=> 8x² - 9x - 4 = 16

<=> 8x² - 9x - 4 - 16 = 0

<=> 8x² - 9x - 20 = 0

( Đến đây bạn có hai sự lựa chọn : 1 là vô nghiệm

                                                         2 là nghiệm vô tỉ =) )

a) (3x + 2)(2x + 9) - (x + 3)(6x + 1) = (x + 1)² - (x + 2)(x - 2)

=> 3x(2x + 9) + 2(2x + 9) - x(6x + 1) - 3(6x + 1) = x² + 2x + 1 - x(x - 2) - 2(x - 2)

=> 6x² + 27x + 4x + 18 - 6x² - x - 18x - 3 = x² + 2x + 1 - x² + 2x - 2x + 4

=> (6x² - 6x²) + (27x + 4x - x - 18x) + (18 - 3) = (x² - x²) + (2x + 2x - 2x) + (1 + 4)

=> 12x + 15 = 2x + 5

=> 12x + 15  - 2x - 5 = 0

=> 10x + 10 = 0

=> 10x = -10 => x = -1

b) (2x + 3)(x - 4) + (x - 5)(x - 2) = (3x - 5)(x - 4)

=> 2x(x - 4) + 3(x - 4) + x(x - 2) - 5(x - 2) = 3x(x - 4) - 5(x - 4)

=> 2x² - 8x + 3x - 12 + x² - 2x - 5x + 10 = 3x² - 12x - 5x + 20

=> (2x² + x²) + (-8x + 3x - 2x - 5x) + (-12 + 10) = 3x² - 17x + 20

=> 3x² - 12x - 2 = 3x² - 17x + 20

=> 3x² - 12x - 2 - 3x² + 17x - 20 = 0

=> (3x² - 3x²) + (-12x + 17x) + (-2 - 20) = 0

=> 5x - 22 = 0

=> 5x = 22 => x = 22/5

c) (x + 2)³ - (x - 2)³ - 12x(x - 1) = -8

=> x³ + 6x² + 12x + 8 - (x³  - 6x² + 12x - 8) - 12x² + 12x = -8

=> x³ + 6x² + 12x + 8 -x³ + 6x² - 12x + 8 - 12x² + 12x = -8

=> (x³ - x³) + (6x² + 6x² - 12x²) + (12x - 12x + 12x) + (8 + 8) = -8

=> 12x + 16 = -8

=> 12x = -24

=> x = -2

Còn bài cuối làm nốt

\(5^{16}:5^{14}+2\times2^3-101^0\)

=\(5^{16-14}+2^{1+3}-1\)

=\(5^2+2^4-1\)

=25+8-1

=33-1

=32

5x+x=39-45:5

6x=39-9

6x=30

x=30:6

x=5

\(=10-\left[\left(91-48\right).5+\left(8.10+8\right)\right]:28\)

\(=10-\left[43.5+88\right]:28\)

\(=10-\left[215+88\right]:28\)

\(=10-303:28\)

\(=10-10,821\)

\(=0,179\)

Ko chắc

\(a.\left(5+2\right).x=36-1\)

\(7.x=35\)

\(x=5\)

\(b.\left(5+1\right).x=75+3\)

\(6.x=78\)

\(x=13\)

\(c.\left(6+1\right).x=5^2+3\)

\(7.x=25+3\)

\(7.x=28\)

\(x=4\)

\(d.\left(7-1\right).x=5^2+3.4-1\)

\(6.x=25+12-1\)

\(6.x=36\)

\(x=6\)

Bài 2 :

a) 5x + 2x = 6² - 5⁰

<=> 7x = 35

<=> x = 5

b) 5x + x = 150 : 2 + 3

<=> 6x = 75 + 3

<=> 6x = 78 

<=>x=13

c) 6x + x = 5¹¹ : 5⁹ +3¹

<=> 7x = 5² + 3

<=> 7x = 28

<=> x = 4

d) 7x - x = 5²¹ :  5¹⁹ + 3 . 2² - 7⁰

<=> 6x = 5² + 12 - 1

<=> 6x = 36

<=> x = 6

1) 5x = 120 : 2

5x = 60

x = 60 : 5

x = 12.

2) 3x + 27 = 45

3x = 45 - 27

3x = 18

x = 18 : 3

x = 6.

3) 73 + x - 122 = 234 : 2

73 + x - 122 = 117

73 + x = 117 + 122

73 + x = 239

x = 239 - 73

x = 166.

4) 32 - 2 ( x - 1 ) = 12

2 ( x - 1 ) = 32 - 12

2 ( x - 1 ) = 20

x - 1 = 20 : 2

x - 1 = 10

x = 10 + 1

x = 11.

5) 3 ( x + 1 ) - 15 = 36

3 ( x + 1 ) = 36 + 15

3 ( x + 1 ) = 51

x + 1 = 51 : 3

x + 1 = 17

x = 17 - 1

x = 16.

6) 32 - ( 4x - 16 ) = 21

4x - 16 = 32 - 21

4x - 16 = 11

4x = 11 + 16

4x = 27

x = 27 : 4

x = 6,75.

7) 13x - 3x = 500

( 13 - 3 )x = 500

10x = 500

x = 500 : 10

x = 50.

8) 9x + x - 35 = 68

9x + 1x - 35 = 68

9x + 1x = 68 + 35

9x + 1x = 103

( 9 + 1 )x = 103

10x = 103

x = 103 : 10

x = 10,3.

1) 5x = 120 : 2

5x = 60

x = 60 : 5

x = 12.

2) 3x + 27 = 45

3x = 45 - 27

3x = 18

x = 18 : 3

x = 6.

3) 73 + x - 122 = 234 : 2

73 + x - 122 = 117

73 + x = 117 + 122

73 + x = 239

x = 239 - 73

x = 166.

4) 32 - 2 ( x - 1 ) = 12

2 ( x - 1 ) = 32 - 12

2 ( x - 1 ) = 20

x - 1 = 20 : 2

x - 1 = 10

x = 10 + 1

x = 11.

5) 3 ( x + 1 ) - 15 = 36

3 ( x + 1 ) = 36 + 15

3 ( x + 1 ) = 51

x + 1 = 51 : 3

x + 1 = 17

x = 17 - 1

x = 16.

6) 32 - ( 4x - 16 ) = 21

4x - 16 = 32 - 21

4x - 16 = 11

4x = 11 + 16

4x = 27

x = 27 : 4

x = 6,75.

7) 13x - 3x = 500

( 13 - 3 )x = 500

10x = 500

x = 500 : 10

x = 50.

8) 9x + x - 35 = 68

9x + 1x - 35 = 68

9x + 1x = 68 + 35

9x + 1x = 103

( 9 + 1 )x = 103

10x = 103

x = 103 : 10

x = 10,3.

a.75-(3.5^2-4.2^3)

=75-(-5)

=80

b.-/-12/+12-(-24)

= - 12 + 12 - 24

=0-24

=-24

c.17.85+15.17-120

=17.(85+15)-120

=17.100-120

=1700-120

=1580

bài 2: tìm x

a. 70-5.(x-3)=45

5.(x-3)=70-45=25

x-3=25:5=5

x=5+3=8

vậy x=8