Răspuns:
2) f=nr de fete
b=nr baieti
Sistem
{b/f=3/5
{f-6=b inlocuiestipe b.
(f-6)/f=3/5
5(f-6)=3f
5f-30=3f
5f-3f=30
2f=30
f=30/2=15
b=15-6=9
total elevi=15+9=24
3)f(x)=ax+b
f(1)=a+b=4
f(-2)= -2a+b=8
Sistem
{a+b=4
{-2a+b=8 Scazi din ecuatia 2 prima ecuatie
-2a+b-a-b=8-4
-3a=4 a=-4/3
-4/3+b=4
b=4+4/3
b=(12+4)/3=16/3
f(x)= -4x/3+16/3
b)a=2 b=3
f(x)=2x+3
(2x+3)/(x-1)+x=5
2x+3+x(x-1)=5(x-1)
2x+3+x²-x=5x-5
x²+x+3-5x+5=0
x²-4x+8=0
Δ=4²-4*8=16-32=-16<0 ecuatia nu admite solutii reale
Explicație pas cu pas:
