Question

x^2 - 20x +c =0
one of the root of the equation is the three times the other, find the values of c and the roots

Answer 1

Let m = one of the roots
Let 3m = the other root (according to the condition given)
Recall that for x^2 + bx + c, the sum of the roots is equal to -b, and the product of roots is equal to c. Therefore,
m + 3m = -(-20)
4m = 20
m = 5 (one root)
3m = 15 (the other root)
c = product of roots = 5*15
c = 75

Hope this helps~ :)