Page 3 - Equations, substitution formulae

c. Seven equal iron balls which are kg each were weighed and had a total mass of 35 .
Determine the value of .

ℎ = 7

35 = 7x

35 7
=
7 7

5 =

= 5 kg

Quadratic equations

Note: anything multiplied by zero is zero

Example: × = 0 It is either = 0 = 0

Examples

Solve the following quadratic equations

a. ( – 4) ( – 2) = 0 b. ( + 2) = 0 c. ( + 9)( + 11) = 0
d. ² + 4 = 0 e. ² + 6 + 9 = 0 f. ² + 2 − 15 = 0

Solutions

a. ( – 4) ( – 2) = 0 b. ( + 2) = 0

ℎ r − 4 = 0 − 2 = 0 ℎ = 0 +
2 = 0

= 4 = 2 = 0 =
− 2