(2a-b) (3a-2b) resultado

CPhill's answer is a good one but it is more common to do it the other way around.

consider this

2(3a) this is 2 lots of 3a and the answer is 2*3a=6a

2(3a+4) is 2 lots of (3a+4) which is 2 lots of 3a plus 2 lots of 4 = 6a+8

(2+3)(3a+4) is 5 lots of (3a+4) but this can also be thought of as 2 lots of (3a+4) plus 3 lots of (3a+4)

so

$$(2a-b)(3a-2b)\\
= 2a(3a-2b) -b(3a-2b)\\
=6a^2-4ab -3ab--2b^2\\
=6a^2-4ab -3ab+2b^2\\
=6a^2-7ab+2b^2\\$$

See, our answers are the same. 

Re: (2a-b) (3a-2b) resultado

We can evaluate this in several ways. One way is to "disrtibute" (multiply) the first expression over both terms in the second. This gives us

[(2a-b)*(3a)]  + [(2a-b)*(-2b)]    which gives us

[6a² - 3ab] + [ -4ab + 2b²]  =

6a² - 3ab - 4ab + 2b²   and combining "like" terms, we have

6a² - 7ab + 2b²

We also could have distributed the second expression over the first.....the answer would have been the same!!!