The teacher will be very surprised to see your correct solution 😉
(a+2)*2*x-20 = 5*a+4*x
a*2+2*2*x-20 = 5*a+4*x
-20 + x*(4 + 2*a) = 5*a+4*x
-20 + x*(4 + 2*a) = 4*x + 5*a
x = 20 + 5*a / ((-4*x + x*(4 + 2*a))/x)
5 10*re(a) 10*I*im(a) x1 = - + --------------- - --------------- 2 2 2 2 2 im (a) + re (a) im (a) + re (a)
x1 = 5/2 + 10*re(a)/(re(a)^2 + im(a)^2) - 10*i*im(a)/(re(a)^2 + im(a)^2)
sum
5 10*re(a) 10*I*im(a) - + --------------- - --------------- 2 2 2 2 2 im (a) + re (a) im (a) + re (a)
=
5 10*re(a) 10*I*im(a) - + --------------- - --------------- 2 2 2 2 2 im (a) + re (a) im (a) + re (a)
product
5 10*re(a) 10*I*im(a) - + --------------- - --------------- 2 2 2 2 2 im (a) + re (a) im (a) + re (a)
=
/ 2 2 \ 5*\im (a) + re (a) + 4*re(a) - 4*I*im(a)/ ----------------------------------------- / 2 2 \ 2*\im (a) + re (a)/
5*(im(a)^2 + re(a)^2 + 4*re(a) - 4*i*im(a))/(2*(im(a)^2 + re(a)^2))