Let f (x) = log2 (x + a) - B, where the image of a given function passes through (- 1,0) (1,1), find the analytic expression and negative interval of real numbers a, B and the function

Let f (x) = log2 (x + a) - B, where the image of a given function passes through (- 1,0) (1,1), find the analytic expression and negative interval of real numbers a, B and the function

(1) Substituting the coordinates of two points, we get
log2(a-1)-b=0
log2(a+1)-b=1
Subtract, get
log2[(a+1)/(a-1)]=1
So (a + 1) / (A-1) = 2
The solution is a = 3 and B = 1
So f (x) = log2 (x + 3) - 1
(2) Let f (x)