a).đkxđ : \(x\ne\dfrac{5}{2}\)
\(\Rightarrow\left(2x-5\right)^2=11^2\)
\(\Leftrightarrow\left(2x\right)^2-2.2x.5+5^2=121\)
\(\Leftrightarrow4x^2-20x+25-121=0\)
\(\Leftrightarrow4x^2-20x-96=0\)
\(\Delta=\left(-20\right)^2-4.4.-96=1936>0\)
=> pt có 2 nghiệm pb
\(x_1=\dfrac{20+\sqrt{1936}}{2.4};x_2=\dfrac{20-\sqrt{1936}}{2.4}\)
<=> \(x_1=\dfrac{20+44}{8}=8\left(tm\right)\)
\(x_2=\dfrac{20-44}{8}=-3\left(tm\right)\)
mấy câu khác bn tự lm ik:v
th lm thêm câu b:v
\(\Rightarrow\sqrt{\left(4x-3\right)^2}=6\)
\(\Leftrightarrow\left(4x-3\right)^2=6^2=36\)
rồi bạn tự giải như nãy í:v
tiếp
c2
a )
\(\Rightarrow x^2-3x+5=\left(x+2\right)^2\)
\(\Leftrightarrow x^2-3x+5=x^2+4x+4\)
\(\Leftrightarrow x^2-3x+5-x^2-4x-4=0\)
\(\Leftrightarrow-7x+1=0\)
=> \(x=-\dfrac{1}{-7}=\dfrac{1}{7}\)
