Question

[Linh My]

Mọi người ơi giúp mình câu 1,2 với

Answer 1

[Nguyễn Lê Phước Thịnh]

Câu 1: 

a: \(\Leftrightarrow6x^2-2x=6x^2-13\)

=>-2x=-13

hay x=13/2

b: \(\Leftrightarrow2x-2x-1=x-6x\)

=>-5x=-1

hay x=1/5

c: \(\Leftrightarrow\left(x+1\right)^2-\left(x-1\right)^2=x^2+3\)

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

\(\Leftrightarrow x^2-4x+3=0\)

=>(x-1)(x-3)=0

=>x=3(nhận) hoặc x=1(loại)

Answer 2

[Trần Tuấn Hoàng]

Bài 4:

\(\left(x^2+x+4\right)^2+8x\left(x^2+x+4\right)+16x^2=0\)

\(\Leftrightarrow\left(x^2+x+4\right)^2+2.4x\left(x^2+x+4\right)+\left(4x\right)^2=0\)

\(\Leftrightarrow\left(x^2+x+4+4x\right)^2=0\)

\(\Leftrightarrow\left(x^2+5x+4\right)^2=0\)

\(\Leftrightarrow\left(x^2+4x+x+4\right)^2=0\)

\(\Leftrightarrow\left[x\left(x+4\right)+x+4\right]^2=0\)

\(\Leftrightarrow\left(x+1\right)^2.\left(x+4\right)^2=0\)

\(\Leftrightarrow\left(x+1\right)^2=0\) hay \(\left(x+4\right)^2=0\)

\(\Leftrightarrow x=-1\) hay \(x=-4\)

-Vậy \(S=\left\{-1;-4\right\}\)