\(d.< =>\left[{}\begin{matrix}2x=0\\x-\dfrac{1}{7}=0\end{matrix}\right.< =>\left[{}\begin{matrix}x=0\\x=\dfrac{1}{7}\end{matrix}\right.\) 

\(e.< =>\dfrac{3}{4}+\dfrac{x}{4}=\dfrac{2}{5}=>\dfrac{x}{4}=-\dfrac{7}{20}=>x=-1,4\)

1)x=21,27,30,33,39,45,60,63

2)0,1,17,34,51

3)x=1,2,3,4,6,12

4)x=7,14,21,28,35,42,49

<=>5/3-2/3=1

<=>10x+55=1555

=>10x=1500

=>x=150

v thi chiu chu biet sao h

\(1.14a.\sqrt{9x^2}-2x=3x-2x=x\)

b)\(2\sqrt{x^2}=2x\)

c)\(3\sqrt{\left(x-2\right)^2}=3x-6\)

d)\(2\sqrt{x^2}-5x=2x-5x=-3x\)

\(e.\sqrt{25x^2}+3x=5x+3x=8x\)

f.\(\sqrt{9x^4}+3x^2=3x^2+3x^2=6x^2\)

g.\(x-4+\sqrt{16-8x+x^2}=x-4+\sqrt{\left(x-4\right)^2}=2x-8\)

Thì cứ xem thầy cô giảng là bt

\(5x^3-5x^2y-10x^2+10xy=5x^2(x-y)-10x(x-y)=(5x^2-10x)(x-y)\)

\(=5x(x-2)(x-y)\)