Sunday

December 21, 2014

December 21, 2014

Posted by **Vanilla** on Saturday, April 7, 2012 at 7:36pm.

f(x) = x^2 + x, x >(or equal to) (-1/2)

Thanks!

- Math -
**Reiny**, Saturday, April 7, 2012 at 10:30pmlet y = x^2 + x , x ≤ -1/2

the inverse is

x = y^2 + y

solving for y ...

y^2 + y - x = 0

y = (-1 ± √(1 - 4x))/2

f(x) = -1/2 ± √(1-4x)/2 where x ≤ 1/4

but in the original we are only considering the left "wing" of the parabola, so in the inverse we have to consider only

f(x) = -1/2 - √(1-4x)/2 , for x ≤ 1/4

testing:

in original, let x = -5

f(-5) = 25-5 = 20 , point is (-5,20)

in the inverse

f(20) = -1/2 - √81/2 = -1/ - 9/2 = -5

**Answer this Question**

**Related Questions**

Calculus - F(x) = 1-x and g(x) = 1/x These functions have the property that f = ...

math - The cost of producing q articles is given by the function C=f(q)=100+2q...

inverse - find f^-1 (x). (this is asking me to find the inverse) f(x) = -(x-2)^2...

Algebra - Myra uses an inverse variation function to model the data for the ...

calculus - f(x) = (x+2)/(x+6) What is f^(-1)(-6)? (what is f inverse of -6) I ...

algebra - 1 (a) A function passes through the points (0, -5), (1, 0), (2, 7). ...

Math 3 - Find the inverse of the function f(x) = 5 – e^(x-1). Determine the ...

pre calculus - Find the inverse of the function below. Graph the function below ...

College Algebra - Find the inverse of the function below. Graph the function ...

precalculus - Find the inverse of the function below. Graph the function below ...