(1+√5)²=1+2√5+5=6+2√5
(√5-√3)(√5+√3)=5-3=2
(3√14+√7):√7-2√2=(3√7*√2+√7):√7-2√2=√7(3√2+1):√7-2√2=3√2+1-2√2=√2+1
X+y=1500 11x+11y=16500
1,1x+1,2y=1720 11x+12y=17200
y=700
x=1500-700=800
А
a/3b
б
-1/9
в
(a-b)(a+b)/(a+3b)*2(a+3b)/[b(a+b)]=2(a-b)/b
г
(c+2)²/[2(c-3)]*(c-3)(c+3)/[5(c+2)]=(c+2)(c+3)/10