Day 1 - Multiplying Binomials

Day 1 - Multiplying Binomials

What if we have

 $\left(5x-9\right)\left(5x-7\right)$  ? There are 2 methods

• Distribute:  $5x\left(5x-7\right)\ \rightarrow\ 25x^2-35x$  

• Distribute:  $-9\left(5x-7\right)\ \rightarrow\ -45x+63$  

• Can we combine like terms?

•  $25x^2-80x+63$  

Multiple Choice

Practice

 $\left(3x-7\right)\left(4x+2\right)$  

•  $7x^2+28x-6x+14$  

•  $12x^2-22x-14$  

•  $12x^2+6x-28x+14$  

The other method - FOIL

 $\left(5x-9\right)\left(5x-7\right)$  

• F - First:  $\left(5x\right)\left(5x\right)$  

• O - Outside:  $\left(5x\right)\left(-7\right)$  

• I - Inside:  $\left(-9\right)\left(5x\right)$  

• L - Last:  $\left(-9\right)\left(-7\right)$  

Poll

 $\left(9x+2y\right)^2$  What do we do here?

•  $81x^2+4y^2$  

•  $\left(9x+2y\right)\left(9x+2y\right)$  , then FOIL

•  $\left(11xy\right)^2$  

Multiple Choice

 $\left(5ab-2\right)^2$  

Practice:

•  $25ab^2+20ab-4$  

•  $25ab-10ab-10ab+4$  

•  $25ab^2-20ab+4$  

Poll

 $\left(4m-2\right)\left(4m^2+5mn+3n^2\right)$  

Can we FOIL this, or just use the distributive property?

• FOIL

• Distribute

 $\left(4m-2\right)\left(4m^2+5mn+3n^2\right)$  

•  $4m\left(4m^2+5mn+3n^2\right)$  

•  $-2\left(4m^2+5mn+3n^2\right)$