needing sum helo here
Commutativity.
If, as is normal, ab represents a times b, etc then ab + ab + cc = 2ab + c2 which is generally not the same as abc.
ab + 2
ab=1a+1b a is equal to either 0 or two, and b is equal to a
The existence of the additive inverse (of ab).
Synthesis reaction A+B=AB
I suppose that you think to synthesis reaction.
This would be a synthesis reaction. General formula A + B yields AB.
An exothermic chemical reaction.
Double-replacement
When many were taught chemistry in the 1970s this was called a double decomposition reaction. It is now called a salt metathesis reaction and also double displacement reaction. There are examples and more information at the related link.
This kind of chemical reaction is usually called "displacement" and sometimes "substitution".
Single replacement
No, It is is a double replacement. AB +CD = AC + BD
An acid plus a base will yield a salt and water. In textbooks this is often written as: HA + BOH yields AB + HOH The above means an acid with its hydronium ion added to a base with its hydroxyl group will yield a salt composed of the acid and the base plus water (hydrogen plus hydroxyl is HOH or H2O).
= (a + b)2 or (a + b)(a + b) (a + b)(a + b) using the FOIL method yields: [multiplying {First Outer Inner Last} and summing the products] = a.a + a.b + b.a + b.b = a2 + ab + ab + b2 = a2 + 2ab + b2
This equation represents an elementary example of a synthesis type reaction. The formula for this reaction is A + B = AB, where A & B are reactants and AB is the product.