7x+21 / x+2=x+3 / 5⇒
5(7x+21) =(x+3) (x+2)
35x+105=x²+5x+6
x²+5x+6-35x-105=0
x²-30x-99=0
Δ=36²⇒x₁=33 si x₂=3
a)abc+bca+cab / xyz+yzx+zxy=100a+10b+c+100b+10c+a+100c+10b+a/100x+10y+z+100y+10z+x+100z+10x+y=111a+111b+111c/111x+111y+111z=111(a+b+c)/111(x+y+z)=a+b+c/x+y+z
b)ab0ab /17 017=10000a+1000b+10a+b/17017=10010a+1001b/17017=1001(10a+b)/17017=10a+b/17
3.x²+x/2x+4=x(x+1)/2(x+2)sete reductibila caci il are pe x+1 si pe x care pot fi nr par si impar si jos cel putin 2 este nr par si s epot reduce
