Which are possible first steps in solving the equation 4^x+3=18?

Trigonometry hellllllpppppppp asap

Find the gradient of f(x,y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

Which math sentence can be used to determine if the triangle is a right triangle?