a/ \(\left(x-4\right)^2-36=0\)
<=> \(\left(x-4-6\right)\left(x-4+6\right)=0\)
<=> \(\left(x-10\right)\left(x+2\right)=0\)
<=> \(\orbr{\begin{cases}x-10=0\\x+2=0\end{cases}}\)<=> \(\orbr{\begin{cases}x=10\\x=-2\end{cases}}\)
b/ \(\left(x+8\right)^2=121\)
<=> \(\left(x+8\right)^2-121=0\)
<=> \(\left(x+8-11\right)\left(x+8+11\right)=0\)
<=> \(\left(x-3\right)\left(x+19\right)=0\)
<=> \(\orbr{\begin{cases}x-3=0\\x+19=0\end{cases}}\)<=> \(\orbr{\begin{cases}x=3\\x=-19\end{cases}}\)
d/ \(4x^2-12x+9=0\)
<=> \(\left(2x\right)^2-2.2x.3+3^2=0\)
<=> \(\left(2x-3\right)^2=0\)
<=> \(2x-3=0\)
<=> \(x=\frac{3}{2}\)
\(c,x^2+8x+16=0\)
\(\Rightarrow x^2+4x+4x+16=0\)
\(\Rightarrow x.\left(x+4\right)+4.\left(x+4\right)=0\)
\(\Rightarrow\left(x+4\right)^2=0\)
\(\Rightarrow x=-4\)
\(d,4x^2-12x+9=0\)
\(4x^2-6x-6x+9=0\)
\(\Rightarrow\left(2.2x^2-2.3x\right)-\left(3.2x-3^2\right)=0\)
\(\Rightarrow2.\left(2x^2-3x\right)-3.\left(2x-3\right)=0\)
\(\Rightarrow2x.\left(2x-3\right)-3.\left(2x-3\right)=0\)
\(\Rightarrow\left(2x-3\right)^2=0\)
\(\Rightarrow2x-3=0\Rightarrow x=1,5\)
Hai phần đầu dễ bãn tự làm
\(x^2+8x+16=0\)
\(x^2+2.4x+4^2=0\)
\(\left(x+4\right)^2=0\)
\(\Rightarrow x+4=0\)
\(x=-4\)
Vậy \(x=-4\)
Tham khảo nhé~
