Решите неравенство3x^2-15x=>0

Question

Решите неравенство
3x^2-15x=>0

Answer 1

3x^2-15x=>0
3x(x-5)=>0
по методу интервалов
+++++++0-----5+++++++
(- бесконечности , 0] U [5, + бесконечность)

Answer 2

3x^2 - 15x = 0 (factor out a 3x) 
3x(x - 5) = 0 (separate parentheses and its coefficient into two equations) 

3x = 0 
x = 0 

x - 5 = 0 
x = 5 

Check: 
3x^2 - 15x = 0 
3(0)^2 - 15(0) = 0 
0 - 0 = 0 
0 = 0 (this is true, so x = 0 is correct) 

3x^2 - 15x = 0 
3(5)^2 - 15(5) = 0 
3(25) - 75 = 0 
75 - 75 = 0 
0 = 0 (this is true, so x = 5 is correct)