Quadratic functions

What is the factors of 2x^2 + 4x -30

Also for x^3+ 5x^2-17x-21 would you still use negative B squared plus or minus the square root of B squared minus 4 times A times C all over 2 times A? Please find it's factors too...

2x² + 4x - 30 = 2(x² + 2x - 15) = 2(x + 5)(x - 3)
I did that one by eye, but you can also use the quadratic formula.
x = [-4 ± √(4² + 4·2·30)]/[2·2]
= [-4 ± √256]/4
= [-4 ± 16]/4
= -5, 3
:::::
x³ + 5x² - 17x - 21
No, you cannot use the quadratic formula, because the equation is cubic, not quadratic.

x³ + 5x² - 17x - 21 = (x - 3)(x + 7)(x + 1)

Yes you would be able to for the first one. if the discriminant (under the square root, B^2-4AC) is <0 it has 2 real zeros meaning it crosses the x axis twice. if it is =0 it has one. if it is less than zero it has two imaginary roots. So,
the first is -2+- square of -240 over 4. square of negative 240 is equal to square of 240 times i (square root of -1) so you write it like -2+-240i over 4. maybe apply the 4 on the bottom, or simplify more if you need to.
second one is a polynomial. to do that you have to do trial and error and just plug in a value for x, or do synthetic division, or long division. then use the formula you get from dividing it to find the other zeros. or you could graph it on a graphing calculator. I'll come back and give you the answer