Let f(x)= |x| and g(x)=x^2

Find all values of x for which f(x)>g(x)

bananapants25 Mar 30, 2024

#1**0 **

To find all values of \( x \) for which \( f(x) > g(x) \), where \( f(x) = |x| \) and \( g(x) = x^2 \), we need to compare their values for different ranges of \( x \).

1. For \( x \geq 0 \):

\[ f(x) = |x| = x \]

\[ g(x) = x^2 \]

So, \( f(x) > g(x) \) for \( x \geq 0 \) when \( x^2 > x \), which is true when \( x > 1 \) or \( x < 0 \).

2. For \( x < 0 \):

\[ f(x) = |x| = -x \]

\[ g(x) = x^2 \]

So, \( f(x) > g(x) \) for \( x < 0 \) when \( -x > x^2 \), which is true when \( -x > x^2 \) for \( x < 0 \).

Let's solve \( -x > x^2 \) for \( x < 0 \):

\[ -x > x^2 \]

\[ x^2 + x < 0 \]

\[ x(x + 1) < 0 \]

This inequality holds true when either \( x < 0 \) and \( x + 1 > 0 \), or \( x > 0 \) and \( x + 1 < 0 \).

1. For \( x < 0 \), \( x(x + 1) < 0 \) when \( x < 0 \) and \( x + 1 > 0 \) (the product of two negative numbers is positive):

\[ x < 0 \]

\[ x + 1 > 0 \]

\[ x > -1 \]

So, for \( x < 0 \), \( f(x) > g(x) \) when \( -1 < x < 0 \).

Combining both ranges of \( x \), we have \( f(x) > g(x) \) for \( x > 1 \) or \( -1 < x < 0 \).

Therefore, all values of \( x \) for which \( f(x) > g(x) \) are \( x \in (-1, 0) \cup (1, \infty) \).

kittykat Mar 30, 2024