show work

simplify:(a-9b)(a+3c)

(a-9b)(a+3c)
a^2+3ca-9ba-9bc

I'm pretty sure this is how you do it... plz check

some standard formula to remember are;

i: (a+b)^2=(a+b)(a+b)= a^2+2ab+b^2

ii: (a-b)^2=(a-b)(a-b)=a^2-2ab-b^2

iii: (a+b)(a-b)= a^2-b^2

look at the patern and work out the logic behind it.

ACTUALLY the logic is ( try to follow);

Given (a+b)(c+d)
the workflow is as follows

a*c +(b*c + a*d)+ bd

e.g. (a+b)(c-d)

NOW IF U HAVE -VE signs, THE TRICK IS TO REMOVE IT ,
(a+b)(c+[-]d)
and u keep the workflow the same as above;

=a*c +(b*c + a*[-]d)+ b*[-]d
=ac +(bc -ad) -bd

u can keep expanding.........

HOPE THIS HELPED U

1 answer

LM = 4 in

MN = ?