Page 67 - A Guide to MATLAB for Beginners and Experienced Users

Practice Set A

Algebra and

Arithmetic

Problems 3–8 require the Symbolic Math Toolbox. The others do not.
1. Compute:
(a) 1111 − 345.
(b) e 14 and 382801π to 15 digits each. Which is bigger?
(c) the fractions 2709/1024, 10583/4000, and 2024/765. Which of these
√
is the best approximation to 7?
2. Compute to 15 digits:
(a) cosh(0.1).
(b) ln(2). (Hint: The natural logarithm in MATLAB is called log, not
ln.)
(c) arctan(1/2). (Hint: The inverse tangent function in MATLAB is called
atan, not arctan.)
3. Solve (symbolically) the system of linear equations

 3x + 4y + 5z = 2
2x − 3y + 7z =−1
x − 6y + z = 3.

Check your answer using matrix multiplication.
4. Try to solve the system of linear equations

 3x − 9y + 8z = 2
2x − 3y + 7z =−1
x − 6y + z = 3.

What happens? Can you see why? Again check your answer using matrix
multiplication. Is the answer “correct”?
4
4
5. Factor the polynomial x − y .
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