数学テスト

Multiplying out brackets (easy)

4(b+1)+3b(b+1)=?

Multiplying out single brackets

To multiply out/expand brackets means multiplying everything inside the bracket by the letter or variable outside the bracket. We call this the Distributive Rule:

$$m(a + b) = ma + mb$$
Example:
$$4(3y+7)=12y+28$$
$$z(z+y−2x)=z^2+zy−2xz$$

Multiplying out double brackets

Two brackets next to each other means the brackets need to be multiplied together. Every term in the first bracket has to be multiplied by every term in the second bracket:

$$(m+n)(a+b)=ma+mb+na+nb$$
Example:
$$(3y+2)(4−y)=$$
$$=3y×4−3y×y+2×4−2×y=$$
$$12y−3y^2+8−2y=$$
$$10y−3y^2+8$$

   
   

Copyright © 2017 - 2020 Eductify