Question 49480
x2 – 15x + 54 = 0 -----------> Equation-1

Quadratic formula for ax2 + bx +c = 0 is:

{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 

from Equation-1,

a=1, b= -15, c=54

Substituting the values of a, b and c into above Quadratic formula to get:

x = {-(-15)+- [sqrt((-15)^2 - 4*1*54)]} / (2*1)

x = {15 +- [sqrt( 225 - 216 )]} / 2

x = {15 +- [sqrt(9)]}/2

x= {15+- 3} / 2

Therefore :

x = ( 15 + 3 ) / 2 and (15 - 3) / 2

x = 18/2 and 12 / 2

Answer:
x = 9, 6
          
Thanks
B.Shridhar