`a)4x(x+1)+(3-2x)(3+2x)=15`

`<=>4x^2+4x+9-4x^2=15`

`<=>4x=6`

`<=>x=3/2`

Vậy `S={3/2}`

`b)3x(x-20012)-x+20012=0`

`<=>3x(x-20012)-(x-20012)=0`

`<=>(x-20012)(3x-1)=0`

`<=>` $\left[\begin{matrix} x=20012\\ x=\dfrac{1}{3}\end{matrix}\right.$

Vậy `S={1/3;20012}`

a) 4x(x + 1) + (3 – 2x)(3 + 2x) = 15

⇔4x² + 4x + (9 – 4x²) = 15

⇔ 4x² + 4x + 9 – 4x² = 15

⇔4x = 15 – 9

⇔x=1,5

b)3x(x – 2001²) – x + 2001² = 0

⇔3x(x – 2001²) – (x – 2001²) = 0

⇔(x – 2001²)(3x – 1) = 0

⇔x – 2001² = 0 hay 3x – 1 = 0

⇔x = 2001² hoặc x = \(\dfrac{1}{2}\)

a) 4x(x + 1) + (3 – 2x)(3 + 2x) = 15

⇔4x2 + 4x + (9 – 4x2) = 15

⇔ 4x2 + 4x + 9 – 4x2 = 15

⇔4x = 15 – 9

⇔4x = 6

⇔x = 3/2

b)3x(x – 20012) – x + 20012 = 0

⇔3x(x – 20012) – (x – 20012) = 0

⇔(x – 20012)(3x – 1) = 0

⇔x – 20012 = 0 hay 3x – 1 = 0

⇔x = 20012 hoặc x = 1/2

x - 100 = 123 - 123

x - 100 = 0

x         = 0 + 100

x         = 100

x-100=123-123

x-100=0

x=100+0

x=100

x-100=123-123

x-100=0

x=0+100

x=100

k nha

(123 + 123 + 224) x 10 * 100 : 10000 = 47

(123+123+224)x10*100:10000=47

\(a,100.123-123.100\)

\(=100.\left(123-123\right)\)

\(=100.0\)

\(=0\)

\(b,10.30+70.10\)

\(=10.\left(30+70\right)\)

\(=10.100\)

\(=1000\)

a) 100 x 123 - 123 x 100

= 100 x ( 123 - 123 )

= 100 x 0

=100

b) 10 x 30 + 70 x 10

= 10 x ( 30 + 70)

= 10 x 10

= 100

sorry, dap so cua cau a là 0, mk đánh nhầm số

=(100x100)+123

=10000+123

=10123

100 x 100 + 123 =

= 10000 + 123

= 10123

100 x 100 + 123

= 10000 + 123

= 10123

Chú bạn học thật giỏi nha ! ! !

là 10123

100*100+123=10123

ai k minh minh k lai

100 * 100 + 123 = 10000 + 123 = 10123

Ai k mk mk k lại 

123 x 100 : 100

= 12300 : 100

= 123

k mk nha

123.100:100

=123.1

=123

k mik
 thanks

\(123x100:100=12300:100=123\)