Consider the steps for solving 3x^2-42x+9=-5

If you are still struggeling:

first we need to get a 0 on one side of the equal sign, cause the formula we're going to be using, needs it.

3x^2-42x+14=0 (go figure this one out :) )

You can use the following formula:

or in phone format:
x_1,_2 = (-b +/- sqrt(b^2 - 4ac))/2a

and in this case a = 3, b = -42 and c = 14. (I highly recommend asking a teacher about why this is, if you cant figure it out on your own.)

then just input values:
x = (-(-42) +/- sqrt( (-42)^2 - 4*3*14))/2*3

do the easy math first, you can do this in as many steps as needed
x = (42 +/- sqrt(1764 - 168))/6
x = (42 +/- sqrt(1596))/6
the sqrt is so close to 40, that i choose to round it up.
x = (42 +/- 40)/6

x_1 = 82/6 = or 13,66666 (....)
x_2 = 2/6 = 1/6

Both of them are the answer. If anyone sees a mistake, please comment. I found the answer to be a bit bad.

If you make it a little more clear i can answer it