#4 (x-4)^(3/2) = -6#
#color(blue)("Squaring both sides"#,
#(4(x-4)^(3/2))^2 = (-6)^2#
#4^2 * (x-4)^((3 * 2)/2) = 36#
#4^2 * (x-4)^3 = 36#
#(x-4)^3 = 36 / 16 = 9 / 4#
#x - 4 = (9/4)^(1/3), " taking cube root on both sides"#
#color(purple)(x = 4 + root3 (9/4)#