Question

chỉ câu này vs ạ mai thi rồi 

Answer 1

a)

\(\left(2x+1\right)^2-4x\left(x+3\right)=9\)

\(4x^2+4x+1-4x^2-12x=9\)

\(4x^2-4x^2+4x-12x+1=9\)

\(-8x+1=9\)

\(-8x=8\\ x=-1\)

b)

\(x^2-12x=-36\\ x^2-12x+36=0\\ x^2-6x-6x+36=0\\ x\left(x-6\right)-6\left(x-6\right)=0\\ \left(x-6\right)^2=0\\ =>x-6=0\\ x=6\)

Answer 2

`a. (2x+1)^2-4x(x+3)=9`
`<=> 4x^2+4x+1-4x^2-12x=9`
`<=> -8x+1=9`
`<=> -8x=8`
`<=> x=-1`
`b. x^2-12x=-36`
`<=> x^2-12x+36=0`
`<=> x^2-2.x.6+6^2=0`
`<=> (x-6)^2=0`
`<=> x-6=0`
`<=> x=6`