!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
(5x+0,1y)(5x-0,1y)=26x^2-0,01y^2
(5a+0,5b)(5a-0,5b)=25a^2-0,25b^2
(0,2a+7b)(0,2a-7b)=0,04a^2-49b^2
(0,9m+0,2n)(0,9m-0,2n)=0,81m^2-0,04n^2
(300:100x60)+(200:100x80)=180+160=340г на 500мл=68%
Девяткой
ееееоевнотвеноентео
(3-3x²)`=-6x
-6x=0
x=0
+ _
-----------------(0)------------------
возр убыв