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LET Reviewer in Math: Sample Topics, Problems and Solution

1. Algebra and Functions

• Solving linear and quadratic equations
• Graphing and analyzing linear and quadratic functions
• Simplifying and solving rational expressions
• Finding the domain and range of functions

2. Geometry

• Properties of triangles, circles, and other polygons
• Perimeter, area, and volume of geometric shapes
• Similarity and congruence of triangles
• Trigonometry and its applications

3. Statistics and Probability

• Measures of central tendency and variation
• Probability rules and concepts
• Permutations and combinations
• Sampling techniques and surveys

4. Calculus

• Limits, derivatives, and integrals
• Applications of calculus to real-world problems
• Optimization problems and related rates

Sample Questions:

1. Solve for x: 2x + 3 = 11
2. Graph the function f(x) = 2x - 5 and find its intercepts.
3. Find the perimeter of a regular hexagon with side length 6 cm.
4. A survey of 500 students found that 200 of them preferred math over science. What is the probability of randomly selecting a student who prefers math?
5. Find the derivative of f(x) = 3x^2 - 4x + 1.
6. An open box is to be made from a rectangular piece of cardboard measuring 24 cm by 36 cm by cutting out squares of equal area from each corner and folding up the sides. What size of square should be cut out to make the box have maximum volume?
7. If sin x = 0.6, what is the value of cos x?

Here are the solutions for the sample questions provided:

1. Solve for x: 2x + 3 = 11
• Solution: Subtract 3 from both sides of the equation: 2x = 8. Divide both sides by 2: x = 4.

2. Graph the function f(x) = 2x - 5 and find its intercepts.
• Solution: To find the y-intercept, set x = 0: f(0) = -5. So the y-intercept is (0, -5). To find the x-intercept, set f(x) = 0: 2x - 5 = 0. Solving for x gives x = 2.5. So the x-intercept is (2.5, 0). The graph of the function is a line with a slope of 2 and a y-intercept of -5.

3. Find the perimeter of a regular hexagon with side length 6 cm.
• Solution: A regular hexagon has six sides of equal length. To find the perimeter, we multiply the length of one side by 6: 6 x 6 = 36 cm. So the perimeter of the hexagon is 36 cm.

4. A survey of 500 students found that 200 of them preferred math over science. What is the probability of randomly selecting a student who prefers math?
• Solution: The probability of selecting a student who prefers math is the number of students who prefer math divided by the total number of students: 200/500 = 0.4 or 40%.

5. Find the derivative of f(x) = 3x^2 - 4x + 1.
• Solution: The derivative of f(x) is f'(x), which is given by the power rule: f'(x) = 6x - 4.

6. An open box is to be made from a rectangular piece of cardboard measuring 24 cm by 36 cm by cutting out squares of equal area from each corner and folding up the sides. What size of square should be cut out to make the box have maximum volume?
• Solution: Let x be the length of each side of the square that is cut out. Then the dimensions of the box will be (36-2x) x (24-2x) x x. The volume of the box is given by V(x) = x(36-2x)(24-2x). To find the maximum volume, we take the derivative of V(x) with respect to x, set it equal to zero, and solve for x. After some algebraic manipulations, we get x = 3 cm. So the size of the square that should be cut out to maximize the volume of the box is 3 cm.

7. If sin x = 0.6, what is the value of cos x?
• Solution: To find cos x, we use the Pythagorean identity: cos^2 x + sin^2 x = 1. Substituting sin x = 0.6 gives: cos^2 x + (0.6)^2 = 1. Solving for cos x gives cos x = ±0.8. Since x is in the first or second quadrant (where cosine is positive), we take the positive value: cos x = 0.8.

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