Quadratic Function

[maroon]

A Quadratic function has the form f(x)=2x^2-7x+c. The point (2, -21) lies on the graph of the function. Determine the value of c.

I haven't had algebra in almost 10 years so I am very rusty and don't even know where to start.

 

[masters]

A Quadratic function has the form f(x)=2x^2-7x+c. The point (2, -21) lies on the graph of the function. Determine the value of c.

I haven't had algebra in almost 10 years so I am very rusty and don't even know where to start.

Hi maroon,

Your point (2, -21) is in the form (x, f(x)). So x = 2 and f(x) = -21.

Substitute these values into your function and solve for c.

\(\displaystyle f(x)=2x^2-7x+c\)

\(\displaystyle -21=2(2)^2-7(2)+c\)

 

[mmm4444bot]

I haven't had algebra in almost 10 years so I am very rusty and don't even know where to start.

It seems like you should start by taking an algebra course, again. If it's review, and you're a decent student type, then you might succeed with self-study on-line.

There are many algebra lessons, on the Internet.

You can use Google, to find specific information. Here are two sites:

http://www.purplemath.com (comprehensive site)

http://www.khanacademy.org/ (short videos)

Are you in some math class now?

Cheers ~ Mark