Exercise 2.5 1 Write if each of the following is a formula, an expression or an equation. \( \begin{array}{ll}\text { a } 3 y+7=35 & \text { b } 6(x+5) \\ \text { c } T=3 a^{2}-8 d & \text { d } 9 u-v w\end{array} \) 2

We need to decide whether each example is a formula, an expression, or an equation. Let’s recall the definitions: • Equation: A statement asserting the equality of two expressions (it has an “=” sign, showing that two sides are equal). • Expression: A combination of symbols (numbers, variables, and operations) representing a value, but without an “=” sign. • Formula: A special type of equation that shows a relationship among variables or quantities. It often expresses one variable in terms of others or relates several variables. Now, let’s look at each example: a) 3y + 7 = 35   This statement has an equals sign and asserts that the left‑hand side equals the right‑hand side.   Answer: Equation b) 6(x+5)   This is a combination of numbers and variables along with arithmetic operations, but there is no “=” sign.   Answer: Expression c) T = 3a² – 8d   This statement includes an equals sign and defines T in terms of a and d. It is not only an equation but also functions as a formula that expresses a relationship among T, a, and d.   Answer: Formula (also an equation, but in a context like this, it is best described as a formula) d) 9u – vw   This is simply an arithmetic combination of variables and does not have an equals sign.   Answer: Expression Thus, the answers are: a. Equation b. Expression c. Formula d. Expression