Currently I'm learning polynomials, trinomials, and basic factoring. I don't understand this question at all.
'a' and 'b' are integers. Find the value of a and b, if a^2 - b^2 = 2 1.
first we think of the factors of 21 that are integers. ok, we can have 21 = 1*21 or 21 = 7*3. now, file that away, we'll come back to it.
Now $\displaystyle a^2 - b^2 = (a + b)(a - b)$ ........the difference of two squares
$\displaystyle \Rightarrow (a + b)(a - b) = 21$
now we want $\displaystyle (a + b)$ and $\displaystyle (a - b)$ to be integer factors of 21.
Let's say they are 7 and 3.
set $\displaystyle a + b = 7$
and $\displaystyle a - b = 3$
$\displaystyle \Rightarrow \boxed{a = 5} \mbox { and } \boxed{ b = 2}$
this is one solution, there are others.
we get a new solution set if a + b = 3 and a - b = 7
and also, if we take the factors to be 1 and 21
we need more conditions if we want a unique solution