First do the ones in the parentheses. So, 2x3=6. 26-6=20. 20^2=400. Now you have 27-4x400. 4x400=1600. 27-1600=-1573.
Y - (-8) = -6 (x-2) is correct everything else is not
y + 8 = -6x + 12
y +:8 - 8 = -6x + 12 - 8
y = -6x + 4 is slope intercept form
Y=2x^3 is nonlinear, since it's a cube equation. y=x+5 is linear, because it's a line with y intercept (0,-5) and slope 1. y=\sqrt(x-5) is nonlinear, because it's a quadratic equation when reversing x and y. 5x+5y=25 is equal to x+y=5 ot y=-x+5, which is also linear. y=x^2/2 is a quadratic equation, so it's nonlinear.
The equation is already is slope intercept form where you can easily point out the gradient, or the slope, and the y intercept.
y=mx+b where m is the gradient, and b is the y intercept.
Since there is no m, the gradient is 1.
The y intercept had x=0 and y=b
b in this case is 6
the y intercept= (0,6)
The answer is the first one hope this helps!!