Multiplying Binomials by Monomials
Today, we started out with an equation to solve.
- ( x + 7 )
How to solve:
= -1 ( x + 7 )
= -1x + (-1)(7)
= -x -7
Next equation:
2(3x + 4)
Solve:
= 2(3x)+2(4) or 3x+4+3x+4
= 6x + 8
This is called distributive property.
The trick to answering an equation is to look at the signs very carefully.
Signs will always confuse you.
(-)(-) Two negatives makes a positive.
(-)(+) One negative makes a negative.
(+)(+) Positives makes a positive.
Example:
-2 ( 3x - 4 )
= -2(3x) + -2(4)
= -6x - 8
2x ( 3x + 4 )
= 2x(3x) + 2x(4)
= 6x ² + 8x
Another way to write this is:
(2)(3)(x)(x) + (2)(4)(x)
Which equals the same thing.
Now a model can be shown:
Another equation is:
-4x (2x - 3y +5)
= -4x(2x) + (-4x)(-3y) + (-4x)(5)
= (-4)(2)(x)(x) + (-4)(-3)(x)(y) + (-4)(5)(x)
= -8x ²+ 12xy -20x
Now one more step is missing; which is the equation has to be in alphabetical order for final answer.
= -8x ²- 20x + 20xy
Homework:
Read pages 264-268
CYU 2 & 3
Practice Odd or Even
2 Apply
Extend - 19 & 20 or 20 & 21
Homework Book 7.2
Extra Practice 7.2
