Slope-intercept form is the easiest to help visualize graphs so you would isolate the y making it y = x^2 - 100. It is now clear to see that this is the parent graph of y=x^2 shifted down 100 units.
Write <em>z</em> in exponential form:

Then taking the logarithm, we get

so a is the correct answer.
That’s the answers hope this helps.
Just pretend it’s a 3d right angle triangle and find the length of the hypotenuse.
d = sqrt(6^2 + 10^2 + 15^2) = 19