Find the value or values of x for which the function is discontinuous.
\large \displaystyle f\left( x \right)=\frac{3x}{x-5}
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Solution:
A function \displaystyle f\left( x \right) is continuous at \displaystyle x=a if \displaystyle \lim_{x \to a} f\left( x \right)=f\left( a \right), which implies these three conditions:
\displaystyle f\left( a \right) is defined.
\displaystyle \lim_{x \to a} f\left( x \right)=L exists, and
\displaystyle L=f\left( a \right)
We are given a rational function. A rational function is not defined when the denominator is equal to zero. If we equate the denominator to zero, we can compute the value/s of \displaystyle x where the function is discontinuous.
The function is not continuous at \displaystyle x=5.
The graph of the function \displaystyle f\left( x \right)=\frac{3x}{x-5} is drawn below. It can be seen that there is an infinite discontinuity at \displaystyle x=5.
A composite bar consists of an aluminum section rigidly fastened between a bronze section and a steel section as shown in Fig. 1-8a. Axial loads are applied at the positions indicated. Determine the stress in each section.
Figure 1.8a
Solution:
We must first determine the axial load in each section to calculate the stresses. The free-body diagrams have been drawn by isolating the portion of the bar lying to the left of imaginary cutting planes. Identical results would be obtained if portions lying to the right of the cutting planes had been considered.
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