a, \(\Delta=\left(-26\right)^2-4.17.9=676-612=64>0\)
Suy ra pt có 2 nghiệm phân biệt
\(\Rightarrow\left\{{}\begin{matrix}x_1=\dfrac{-\left(-26\right)+\sqrt{64}}{2.17}=\dfrac{26+8}{34}=\dfrac{34}{34}=1\\x_2=\dfrac{-\left(-26\right)-\sqrt{64}}{2.17}=\dfrac{26-8}{34}=\dfrac{18}{34}=\dfrac{9}{17}\end{matrix}\right.\)
\(b,\Delta=\left(4\sqrt{7}\right)^2-4.3.4=112-48=64>0\)
Suy ra pt có 2 nghiệm phân biệt
\(\Rightarrow\left\{{}\begin{matrix}x_1=\dfrac{-4\sqrt{7}+\sqrt{64}}{2.3}=\dfrac{-4\sqrt{7}+8}{6}=\dfrac{4-2\sqrt{7}}{3}\\x_2=\dfrac{-4\sqrt{7}-\sqrt{64}}{2.3}=\dfrac{-4\sqrt{7}-8}{6}=\dfrac{-4-2\sqrt{7}}{3}\end{matrix}\right.\)
a: \(\Leftrightarrow17x^2-17x-9x+9=0\)
=>(x-1)(17x-9)=0
=>x=1 hoặc x=9/17
b: \(\Delta=\left(4\sqrt{7}\right)^2-4\cdot3\cdot4=64>0\)
Do đó: Phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{-4\sqrt{7}-8}{6}=\dfrac{-2\sqrt{7}-4}{3}\\x_2=\dfrac{-2\sqrt{7}+4}{3}\end{matrix}\right.\)
