Simplify the given rational expression by completing the step 5c^2-15c^3/20c^2d+25c^2just answered it answer was last option

For this case we have the following expression:
 (5c ^ 2-15c ^ 3) / (20c ^ 2d + 25c ^ 2)
 We make common factor c ^ 2:
 (c ^ 2 (5-15c)) / (c ^ 2 (20d + 25))
 We do common factor 5:
 (5c ^ 2 (1-3c)) / (5c ^ 2 (4d + 5))
 Canceling similar terms we have:
 (1-3c) / (4d + 5)
 
 The simplified expression is given by:
 (1-3c) / (4d + 5)

X^4 + 36x^2 = x^2(x^2+36)= x*x*(x+6i)(x-6i) mark me brainliest