a) \(36x^2-1-\left(36x^2-36x+9\right)=8\)
\(36x^2-1-36x^2+36x-9-8=0\)
\(36x=18\)
\(x=\dfrac{1}{2}\)
c)\(64x^2-48x+9-\left(64x^2+144x+81\right)=12\)
\(64x^2-48x-3-64x^2-144x-81=0\)
\(-192x=84\)
\(x=-\dfrac{7}{16}\)
a) Ta có: \(\left(6x-1\right)\left(6x+1\right)-\left(6x-3\right)^2=8\)
\(\Leftrightarrow36x^2-1-36x^2+36x-9-8=0\)
\(\Leftrightarrow36x=18\)
hay \(x=\dfrac{1}{2}\)
b) Ta có: \(\left(5x-4\right)\left(5x-8\right)+\left(5x+3\right)^2=7\)
\(\Leftrightarrow25x^2-60x+32+25x^2+30x+9-7=0\)
\(\Leftrightarrow50x^2-30x+34=0\)
\(\Delta=\left(-30\right)^2-4\cdot50\cdot34=900-6800< 0\)
Do đó: Phương trình vô nghiệm
c) Ta có: \(\left(8x-3\right)^2-\left(8x+9\right)^2=12\)
\(\Leftrightarrow\left(8x-3-8x-9\right)\left(8x-3+8x+9\right)=12\)
\(\Leftrightarrow16x+6=-1\)
\(\Leftrightarrow16x=-7\)
hay \(x=-\dfrac{7}{16}\)
