since 2/3 of all the students study a language and 2/5 of those study french. 2/3 x 2/5 or 4/15 of the entire student body study french.
lets start by factorizing the expression 16x²+40xy+25y²
consider the expression ax²+bx+c
during factorization, two numbers picked should add up to b while the product should be=ac
we find two numbers that when added give 40 and when multiplied = 16×25=400
these numbers are 20 and 20
therefore the expression will be broken into:
the expression is a perfect square.