A quadratic equation is of the format:
ax² + bx + c = 0, where a ≠ 0.
The first option is not quadratic, it is a cubic, it has highest power of 3.
The second option f (x) = 3/4 x ^2 + 2x − 5, is quadratic, that is the answer.
The third f(x) = 4/x^2 - 2/x + 1, doesn't qualify because of the 2/x.
The last f(x) = 0x^2 − 9x + 7
, doesn't qualify because of the a = 0, and the rule is that a ≠ 0.
Therefore f (x) = 3/4 x ^2 + 2x − 5 represents a quadratic function.
I hope this helps.
