Math Minute 40

Front

What is the formula for the perimeter of a rectangle?

Back

Perimeter = 2(length + width)

Front

If the length of a rectangle is (5x - 3) and the width is (x + 3), how do you find the perimeter when x = 2?

Back

Substitute x = 2 into the expressions: Length = 5(2) - 3 = 7, Width = 2 + 3 = 5. Perimeter = 2(7 + 5) = 24.

Front

Evaluate the expression -4n - n² for n = 3.

Back

Substitute n = 3: -4(3) - (3)² = -12 - 9 = -21.

Front

What is the area of a rectangle with dimensions (2c + 1) and (3 + c) when c = 3?

Back

Substitute c = 3: Length = 2(3) + 1 = 7, Width = 3 + 3 = 6. Area = Length × Width = 7 × 6 = 42 square units.

Front

How do you evaluate an expression with two variables, such as 3x - 4y, when x = 2 and y = 3?

Back

Substitute x = 2 and y = 3: 3(2) - 4(3) = 6 - 12 = -6.

Front

What is the value of u² if u = 5?

Back

u² = 5² = 25.

Front

What is the value of 3t - u² when t = 3 and u = 5?

Back

Substitute t = 3 and u = 5: 3(3) - 5² = 9 - 25 = -16.

Front

What is the definition of a variable in mathematics?

Back

A variable is a symbol used to represent an unknown value or a value that can change.

Front

What does it mean to evaluate an expression?

Back

To evaluate an expression means to calculate its value by substituting the variables with given numbers.

Front

What is the formula for the area of a rectangle?

Back

Area = length × width.