Add the following
-6a2-9b2,7a2+2b2,-3a2-4b2
To add two or more algebraic expressions, group the like terms of the expression and add each group of like terms separately.
The Sum
=(-6a2-9b2)+(7a2+2b2)+(-3a2-4b2)=(-6a2+7a2-3a2)+(-9b2+2b2-4b2)(grouping the like terms)
adding the numerical coefficient of like terms
=(-6+7-3)a2+(-9+2-4)b2=(7-9)a2+(-13+2)b2=-2a2+(-11)b2=-2a2-11b2