Question

Giải phương trình:

3x^2 + 5x - 2 = 0

Answer 1

`3x^2+5x-2=0`

Ptr có:`\Delta=b^2-4ac=5^2-4.3.(-2)=49 > 0`

  `=>` Ptr có `2` nghiệm pb

`x_1=[-b+\sqrt{\Delta}]/[2a]=[-5+\sqrt{49}]/[2.3]=1/3`

`x_2=[-b-\sqrt{\Delta}]/[2a]=[-5-\sqrt{49}]/[2.3]=-2`

Vậy `S = {1/3 ; -2}`

Answer 2

\(3x^2+5x-2=0\)

\(\Delta=5^2-4.3.\left(-2\right)=25+24=49>0\)

--> pt có 2 nghiệm

\(\left\{{}\begin{matrix}x_1=\dfrac{-5+\sqrt{49}}{6}=\dfrac{1}{3}\\x_2=\dfrac{-5-\sqrt{49}}{6}=-2\end{matrix}\right.\)