(36*c²-6*5*2*c+25)/(5-6*c)*(5+6*c)=-(6*c-5)²/(6*c-5)*(6*c+5)=(5-6*c)/6*c+5)
m*n+3*m-n²-3*n=m*(n+3)-n*(n+3)=(n+3)*(m-n)
(36*c²-6*5*2*c+25)/(5-6*c)*(5+6*c)=-(6*c-5)²/(6*c-5)*(6*c+5)=(5-6*c)/6*c+5)
m*n+3*m-n²-3*n=m*(n+3)-n*(n+3)=(n+3)*(m-n)