Today in class we learned about a negative in front of a bracket and adding and subtracting polynomials.
eg. 55x + 30 - (22x + 20) you can't leave it this way so it becomes: 55x +30 -22x - 20
A negative in front of a bracket means: the opposite of everything in the bracket.
Why? -( means -1 multiplying everything inside the bracket
- use models
(3x -4) + (2x +5) = 5x + 1- use symbols
(3x + 4) + (2x + 5)
=3x + 2x - 4 + 5
= 5x + 1
- add the opposite
(3x - 4) - (2x + 3)
= (3x - 4) + (-2x - 3)
= 3x - 2x -4 - 3
= x - 7