1NA Mathematical Formulae

A formula is an _____________ that expresses the relationship between certain quantities or variables.

Given that y = 2x + 5.

Find the value of y when x = 7.

Answer explanation

y = 2x + 5

y = 2(7) + 5

y = 14 + 5

y = 19

Answer explanation

Find the formula for the sum S of any three consecutive odd numbers.

Answer explanation

Find a formula for average A of three numbers a, b and c.

• A = 3(a+b+c)

The total mass M, in grams, of p notepads and q books is given by M = 25p + 120q.

There are 6 notepads and twice as many books. Find the total mass.

• 390g

• 1590g

• 770g

• 1020g

Answer explanation

Note that the number of books is twice the number of notepads.

Since there is 6 notepads, there is 12 books.

Substitute p = 6 and q = 12 into the formula M = 25p + 120q

• 27

• 54

• 48

• 30

Answer explanation

"the base is 9 cm and the height is 6 cm" means b = 9 and h = 6

• 7.5

• 750

• 145

• 30

Answer explanation

"the area is 75 cm² and the base is 5 cm"

means A = 75 and b = 5

Evaluating formula refers to find the value of 1 variable in a given formula when given the values of the other variables.

I have learnt how to evaluate formula.

• Strongly agree

• Agree

• Disagree

• Strongly Disagree

Constructing formulae refers to forming an equation that expresses the relationship between certain variables.

I have learnt to construct formula given the information relating the variables.

• Strongly agree

• Agree

• Disagree

• Strongly disagree