Answer: the sum of 9 a + 3 b – 1 and – 2 a – 5 explanation:Adding and subtracting terms
You can only add or subtract terms if they are the same type of terms.
It may help to think of a thermometer when combining positive and negative terms.
Expanding a bracket
When there is a number (or letter) in front of a bracket, it means everything inside the bracket
must be multiplied by that number (or letter).
Remember the rules for signs when multiplying or dividing positive and negative quantities:
Examples 3(2 x +1) = 6 x +3 a(a −b) = a − ab 2
Expanding 2 brackets
When two brackets are multiplied, each term in the first is multiplied by each term in the second.
Examples (2 x − 3) (4 x + 5) = 8 x + 10 x − 12 x −15 2
= 8 x − 2 x −15 2
Here are more examples of expanding brackets and simplifying.
Examples 5(x – 2
4 + y) + 3 x(x – y) = 4 x
2 + 4 x 2
– 3 x y = 7 x
2
+ x y
(5 a – b)(2 a – 3 b) = 10 a
2
– 15 ab – 2 ab + 3 b
2
= 10 a
2
– 17 ab + 3 b
2
