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Mathematical Equation Problem Equation k(x squared -4)+ax- 1=0 has real roots for all real numbers K. Try to find the range of the real number A. 。
kx^2+ax- 1-4k=0

k=0,ax = 1-& gt; a & lt& gt0

k & lt& gt0,delta=a^2+4k( 1+4k)>; =0=a^2+ 16k^2+4k=a^2+ 16(k+ 1/8)^2- 1/4>; =0

k=- 1/8,a^2- 1/4>; = 0->; A>= 1/2 or a & lt=- 1/2.

So the result is: a>= 1/2 or a & lt=- 1/2.