Question

Hi,

When I have a quadratic equation, ax^2 + bx + c, can I find the y-intercept by looking at the last digit like I can when I have a linear equation?

For example, 3x^2 + 10x + 2, the y-intercept is (0, 2)

To check, if I make x = 0, 3(0)^2 + 10(0) + 3 = 3, so my y-intercept is (0, 3), so it checks out, but does this always work for quadratic equations?

Thank you

Answer 1

sure ... making x=0 puts you on the y-axis ... so that's the y-intercept

Answer 2

So I can always just look at the last number of the equation, though, to see what the y-intercept is??

Answer 3

yes, that works for any polynomial in standard form (descending powers of the variable).
Don't be surprised if it happens to come out zero, though, as with
y = 2x^2 - 5x