Question

does the graph of y=3x^2-x-2 open up or down? explain.

Answer 1

Check the leading coefficient.

Answer 2

is it stupid that i have no idea what that is.... sorry, im terrible at math

Answer 3

You can also explore this by completing the square, finding the vertex, and plotting some points around it to see what the graph looks like.

Answer 4

Erm.. no, not "stupid" necessarily, you just might not have been exposed to the standard vocabulary.

Answer 5

do i need to do the quadratic formula to figure out the points to plot?

Answer 6

For a polynomial in standard form, in this case a quadratic of the form ax^2 + bx + c, a is the leading coefficient (because it's in front).

Answer 7

Not nessesarily.

Think of a value for x (say 0) then plug and chug.

keep on going (1,2,3,4...) until you have some point to work with.

Connect the dots.

Answer 8

No, no quadratic formula necessary, but that would help you find the x-intercepts (if any).
For this, there's a really easy short cut. If the leading coefficient is positive, then it is concave upwards (opens up), if negative, then down.

Think of graphing the parabola, if the leading coefficient is positive, then smiley face!

Answer 9

That's the easy but time consuming method. There are other ones,too.

Answer 10

thank you so much! i was just confused because i thought that if the leading coefficient was positive then it went upward but i wasnt sure