The quotient rule is
d(u/v) = (u dv - v du) / u2
d(u/v) can written as
d( u (1/v) )
Using the product rule and chain rule
d( u (1/v)) = u d(1/v) + (1/v) du
= u (-1/v2) dv + (!/v) du
= (u dv - v du) / u2
It is an isosceles triangle
5x + 50 +x
= 5x*2( square ) + 50