Question

Ajutor la 15,16,18, dau coroana.

Answer 1

(x+y)²=x²+2xy+y²=13+12=25
x+y=5
care impreuna cu xy=6 determina ecuatia care ne va furniza solutiile
x²-Sx+P=0
x²-5x+6=0
x=5-1/2=2
y=5+1/2=3 deoarece x<y

relatia de proportionalitate se scrie a/2=b/5 deci a=2/5*b   a=0,4*b=40%b
2a+3b=57 /*2
5a-2b=0 /*3   4a+15a=2*57   19a=2*57   a=6   si b=5/2*6=15

E(x)=(2x-3)²-3x(x-4)-(x-1)(x+1)=4x²+9-12x-3x²+12x-x²+1=10 independenta de x si numar natural