(2)mOA-2 *(OA+AB)+OA+AC = 0;
Simplify to get (m-1) * OA = 2ab-AC; Can you know A through painting? b? C*** line, so 2AB-AC is also on the original line, and the vectors should be equal, but the length and direction are different. Pay attention to the direction of OA Is it used? Answer? b? C direction is different, only m- 1=0.
So m =1;
(3)f(x) is the increasing function in the interval [- 1, 1], and f(x)
So t*t-2at+ 1= > 1, we can know that a belongs to [- 1, 1], so let a be the unknown and t be the parameter; You can know-2t * a+t * t >; =0, this is a straight line with a slope of -2t and a domain of-1 and 1.
In two cases?
Answer.-2t > 0,-2t * 1+t * t & gt; =0; -2t *( 1)+t * t & gt; =0? Get t
B.-2t <; 0,-2t * 1+t * t & gt; =0; -2t *( 1)+t * t & gt; =0 to obtain t & gt=2;
C, -2t=0 gives t = 0;; Clearly established
When combining (negative infinity, -2) and {t=0} and [2, positive infinity)