# Value of B

• Jun 11th 2007, 12:48 PM
blueridge
Value of B
If f(x) = 3x^2 -Bx + 4 and f(-1) = 12, what is the value of B?

Must I plug -1 for x in the given trinomial?

Why is 12 given as a result in terms of f(-1)?
• Jun 11th 2007, 01:12 PM
Jhevon
Quote:

Originally Posted by blueridge
If f(x) = 3x^2 -Bx + 4 and f(-1) = 12, what is the value of B?

Must I plug -1 for x in the given trinomial?

Why is 12 given as a result in terms of f(-1)?

yes, plug in x = -1 in the function and equate it to 12 as directed. B will be the only unknown, just solve for it

f(-1) = 12 means, when the input is -1 the output is 12
• Jun 11th 2007, 03:57 PM
blueridge
ok
What would be the purpose for solving for B in questions like this one?
• Jun 11th 2007, 04:01 PM
Jhevon
Quote:

Originally Posted by blueridge
What would be the purpose for solving for B in questions like this one?

well, there are times when you want to find a certain type of function that behaves a certain way for whatever reason, and so using a similar method to this, you can find such a function.

let's say you want to find a cubic polynomial that will go through certain points. you could say that the polynomial is of the form y = ax^3 + bx^2 + cx + d, and use properties like these to find the particular function