Answer:
[tex]3x^2 + 5x - 7 = 0[/tex], [tex]5x^2+ 15x = 0[/tex] and [tex]x2 - 4x = 4x + 7[/tex] are quadratic equations.
Step-by-step explanation:
We are required to find the quadratic equations.
Now, as we know,
Quadratic equation is an equation having degree 2 and is of the form [tex]ax^2+bx+c=0[/tex].
So, according to the options, we see that,
The equations [tex]x^3 - 2x^2 + 1 = 0[/tex], [tex]2x - 1 = 0[/tex] and [tex]6x - 1 = 4x + 7[/tex] have degree 3, 1 and 1 respectively.
Thus, these equations are not quadratic equations.
Hence, the equations 1, 4 and 6 are quadratic equations.
