3rd:

3. Solve for x: (x-1)(x+3)(x-2)(x-6)+36=0

(x-1)(x+3)(x-2)(x-6)+36=0 (x^2+2x-3)(x^2-8x-12)+36=0 x^4-6x^3-7x^2+48x=0 x^3-6x^2-7x+48=0 (If x=3 then the equation turns out to be zero) x^2(x-3)-3x(x-3)-16(x-3)=0 (x-3)(x^2-3x-16)=0 Therefore, X=3