What is the range of f(x)= 2/(x^2-2x-3) ?

The range of f(x)= 2/(x^2-2x-3) is f(x) 0

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range of f(x)= 2/(x^2-2x-3)

range

f (x) = \frac{2}{x ^{2} - 2 x - 3}

f (x) \leq - \frac{1}{2} or f (x) > 0

Solution steps

Rewrite as

\frac{2}{x ^{2} - 2 x - 3} = y

Multiply both sides by

x^{2} - 2 x - 3

2 = y (x^{2} - 2 x - 3)

The range is the set of y for which the discriminant is greater or equal to zero

Discriminant

2 = y (x^{2} - 2 x - 3) : 16 y^{2} + 8 y

16 y^{2} + 8 y \geq 0 : y \leq - \frac{1}{2} or y \geq 0

Check if the range interval endpoints are included

y = - \frac{1}{2} :

Included

y = 0 :

Excluded

Therefore the range is

f (x) \leq - \frac{1}{2} or f (x) > 0

f (x) = y

f (x) = \frac{3}{2 x - 4}

(x - 7)^{2} - 8

f (x) = x

f (x) = 2 x^{3} - 24 x - 2

What is the range of f(x)= 2/(x^2-2x-3) ?
The range of f(x)= 2/(x^2-2x-3) is f(x)<=-1/2 \lor f(x)>0