Friday, June 16, 2017

College Algebra, Chapter 1, 1.6, Section 1.6, Problem 66

Solve the nonlinear inequality $\displaystyle \frac{3}{x-1} - \frac{4}{x} \geq 1 $. Express the solution using interval notation and graph the solution set.

$
\begin{equation}
\begin{aligned}
\frac{3}{x-1} - \frac{4}{x} \geq 1\\
\\
\frac{3}{x-1} - \frac{4}{x} - 1 & \geq 0 && \text{Subtract } 1\\
\\
\frac{3x-4(x-1)-x(x-1)}{x(x-1)} & \geq 0 && \text{Multiply LCD } x(x-1)\\
\\
\frac{3x-4x+4-x^2+x}{x(x-1)} & \geq 0 && \text{Simplify the numerator}\\
\\
\frac{-x^2+4}{x(x-1)} & \geq 0&& \text{Factor out negative } 1\\
\\
\frac{-(x^2-4)}{x(x-1)} & \geq 0 && \text{Divide by } -1 \\
\\
\frac{x^2 - 4}{x(x-1)} & \leq 0 && \text{Difference of squares}\\
\\
\frac{(x+2)(x-2)}{x(x-1)} & \leq 0

\end{aligned}
\end{equation}
$


The factors on the left hand side are $x$, $x+2$, $x-2$ and $x-1$. These factors are zero when $x$ is 0,-2,2 and 1 respectively. These numbers divide the real line into intervals
$(-\infty, -2], (-2,0), (0,1),(1,2),[2,\infty)$




From the diagram, the solution of the inequality $\displaystyle \frac{(x+2)(x-2)}{x(x-1)} \leq 0$ are
$[-2,0) \bigcup (1,2]$

No comments:

Post a Comment

Summarize the major research findings of "Toward an experimental ecology of human development."

Based on findings of prior research, the author, Bronfenbrenner proposes that methods for natural observation research have been applied in ...