posted by lee on .
Can someone please explain
What polynomial has a graph that passes through the given points?
(–4, 89), (–3, 7), (–1, –1), (1, –1), (4, 329)
y = 2x3 – 3x2 – 2x + 1
y = 1x4 – 2x3 – 3x2 + 2x + 1
y = x4 – 2x3 + 3x2 + 2x – 1
y = x4 + 2x3 – 3x2 – 2x + 1
what, you can't plug in the values and evaluate?
329 is greater than 4^3, so y is obviously a 4th-degree polynomial.
4^4 = 256, so I'd try the last one:
256 + 2*64 - 3*16 - 2*4 + 1 = 329, so check the other values. Looks like the one.
so you think
I don't understand these problems
It's not too complicated. They gave you a list of x and y values. All you have to do is plug in the x values and see whether one of the functions produces the correct y values.
The point of these exercises is just to see whether you can evaluate expressions using various values.
Looks like you need to spend some time graphing functions and evaluating expressions.
You can play around with such things at
Toward the bottom there's an area where you can type in a function and give it values. That's what I did once I had seen that x^4+2x^3-3x^2-2x+1 produced 329 for x=4.
The only way to get comfortable with this stuff is to play around with it for a few hours.