Question

Which represents a quadratic function?

f(x) = −8x3 − 16x2 − 4x
f (x) = x 2 + 2x − 5
f(x) = + 1
f(x) = 0x2 − 9x + 7

Answer 1

quadratic functions are of the form
ax^2+bx+c
where 'a' must be nonzero

Answer 2

the degree (aka largest exponent) is 2

Answer 3

okay i think its the first one

Answer 4

no, that's a cubic function

Answer 5

\[f(x)=-8x^{3}-16x^{2}-4x\]\[f(x)=x^{2}+2x-5\]\(f(x)=+1\) ??? is this missing something?\[f(x)=0x^{2}-9x+7\]

Answer 6

The leading term in a quadratic equation is a number followed by \(x^{2}\). And the last one doesn't count because 0 times anything is 0 and cancels the whole thing out.\[f(x)=0x^{2}-9x+7\rightarrow f(x)=\cancel{0x^{2}}-9x+7\]

Answer 7

Example of a quadratic
\[\Large -16x^2+100x+140\]
notice how the largest exponent is 2 (degree = 2)
------------------------------
\[\Large {\color{red}{-16}}x^2+{\color{green}{100}}x+{\color{blue}{140}}\]
is in the form
\[\Large {\color{red}{a}}x^2+{\color{green}{b}}x+{\color{blue}{c}}\]

where
\[\Large \color{red}{a = -16}\]
\[\Large \color{green}{b = 100}\]
\[\Large \color{blue}{c = 140}\]

Answer 8

so it would be on of the fractions ?

Answer 9

you mean something like choice C? no, because you cannot have a variable in the denominator like that

Answer 10

no not choice c but choice b

Answer 11

http://www.mathsisfun.com/algebra/polynomials.html

look at the section where they describe what makes a polynomial and what doesn't make a polynomial

Answer 12

\(\frac{4}{x^{2}}\) is \(not\) a quadratic because that would be \(4\times\frac{1}{x^{2}}\) or \(4\times x^{-2}\)

Answer 13

yes it's choice b because it's in the form ax^2+bx+c

in the case of choice B, we have
a = 3/4
b = 2
c = -5

Answer 14

okay I saw what you were talking about on the website

Answer 15

thank you guys

Answer 16

No problem. ☺\[\text{Happy Openstudying!}\]