題目
a)12x^2-16kx+5k^2=0 is a quadratic equation in x where k is an interger.It is given that 3/2 is a root of the equation.By using the quadratic formula,find
a)the value of k,
b)the other root of the equation.
答案
a) x = {16k + √[(16k)^2 - 4(12)(5k^2)]}/2(12)
or
x = {16k - √[(16k)^2 - 4(12)(5k^2)]}/2(12)
x = 5k/6 or x = k/2 <----------------請問呢步點出?
As k is an integer, k should be 3 <-------------------------------呢到又點解會係3?
(b) The other root is 5k/6 = 15/6 = 5/2<------------點解other root係5k/6而唔係k/2?