Question 10104
{{{3x^2 = 75}}}. Why the hell would they ask you to factorise this? Complete waste of effort! Anyway, here goes:


{{{3x^2 - 75 = 0}}}
{{{x^2 - 25 = 0}}}
{{{x^2 - 5^2 = 0}}}
(x+5)(x-5) = 0


So either x+5=0 OR x-5=0
so, either x=-5 or x=+5


CHECK:
put x=5 into {{{3x^2}}} --> you should get 75 as answer
put x=-5 into {{{3x^2}}} --> you should get 75 as answer


My solution is:
{{{3x^2 = 75}}}
{{{x^2 = 25}}}
{{{x = sqrt(25)}}} OR {{{x = - sqrt(25)}}}
--> x=+5 or x=-5


much simpler!


jon.