Evaluate an expression/formula
We can find the value of an expression when given the values of \(x\), \(y\), etc.
Before we start, we will need to remind ourselves of This is the order in which arithmetic operations must be carried out. Brackets - Of - Divide - Multiply - Add - Subtract.: the order in which we carry out calculations.
Question
Find the value of \(3x + 5y\) when \(x = 2\) and \(y = -1\).
To find the value of an expression, we need to substitute the given values for \(x\) and \(y\) into \(3x + 5y\).
\(3x + 5y\)
\( = 3 \times 2 + 5 \times ( - 1)\)
Remember, BODMAS tells us to multiply before we add.
\(= 6 + ( - 5)\)
\(= 1\)
Question
Evaluate \(5c - b + 2a\) when \(a = 3\), \(b = 1\) and \(c = 4\).
\(5c - b + 2a\)
\(= 5 \times 4 - 1 + 2 \times 3\)
\(= 20 - 1 + 6\)
\(= 25\)
Question
An approximate formula which converts celsius temperatures to farenheit is \(F = 2C + 30\).
Calculate \(F\) when \(C\) is 15.
\(F = 2C + 30\)
\(F = 2 \times 15 + 30\)
\(F = 30 + 30\)
\(F = 60\)
Therefore 15°C is approximately equal to 60°F.
