c)\(DK.x>=3\)

\(3\sqrt{\dfrac{25\left(x-3\right)}{9}}+2\sqrt{x-3}-\dfrac{1}{2}2\sqrt{x-3}=12\)

\(3\sqrt{x-3}+\sqrt{x-3}=12=>4\sqrt{x-3}=12\)

=>\(\sqrt{x-3}=3\)=>\(x-3=9=>x=12\)

loai 2 ve nay k TMDKXD

\(a)5(1-x)-10=0\)\(=>x=1\)

\(b)2x+1=x-9=>x=-10\)(bình phuong 2 vế )

\( (x + 2)(2x - 4) - (2x + 1)^2 + 2x(x - 3)\)

\(<=>2x^2-4x+4x-8-(4x^2+4x+1)+2x^2-6x\)

\(<=>-10x-9\)

Thay x=1/5

=>A=-11

\(\dfrac{x+8}{x+1}=1+\dfrac{7}{x+1}\)

Gọi số cần tìm là ab

Ta có: 4ab + ab = 464

400 + ab + ab = 464

400 + 2 x ab = 464

=>ab  = 32

Vậy số cần tìm la 32

ab x 2 = 64

a) x-35-120=0

=)x=155

b)15x-525=0

x=35

c)10+5x=75

=>5x=65

=>x=13

\((x-3)^2-(x-1)^3+(x-5)(x+5)+(x+1)\)

\(x^2-6x+9-(x^3-3x^2+3x-1)+(x^2-5^2)+x+1\)

x=1