83.
{-10,-6,-5,-4,-2.5,-1,0,2.5,4,6,7,10 }
A number is to be selected at random from the set above. What is the probability that the number selested will be
a solution of the equation(x-5)(x+10)(2x-5)=0?
我的想法是
用1去剪掉C12取3個(當分母),分子是2(-10和-2.5)
就是全部剪掉會同時發生的情況
但是X-5該怎麼辦呢?
想請大家幫我解答一下
謝謝:)