Question

Which function is a quadratic function?u(x) = –x + 3x2 – 8v(x) = 2x2 + 8x3 + 9xy(x) = x2 + 3x5 + 4z(x) = 7x2 + 2x3 – 3

Answer 1

Answer:

$u(x) = -x + 3x^2 - 8$

Step-by-step explanation:

Quadratic function is in the form of $y=ax^2+bx+c$ with largest exponent as 2

$u(x) = -x + 3x^2 - 8$ can be written as $u(x) =3x^2-x - 8$

is in the form of y=ax^2 + bx +c with largest exponent 2. so it is quadratic function.

$v(x) = 2x^2 + 8x^3 + 9x$. It is not quadratic because it has largest exponent 3.

$y(x) = x^2 + 3x^5 + 4$. It is not quadratic because it has largest exponent 5.

$z(x) = 7x^2 + 2x^3 - 3$ It is not quadratic because it has largest exponent 3.

Answer 2

The quadratic function:

$f(x)=ax^2+bx+c,\ a\neq0$

Answer: $u(x)=-x+3x^2-8=3x^2-x-8$