Răspuns:
Explicație pas cu pas:
a) x²=5²-4²=1×9 x=±3
b) x²=13²-5²=(13-5)(13+5)=8×18=2³×2×3² x=±12
c)21+2x²=x²-15 x²=-36 nu are solutii reale
d) x(x-3)=(x+4)(1-x) x²-3x=-x²-3x+4 2x²=4 x=±√2
e) x²/4+x=x²/5+x x²/4=x²/5 x=0
f)2/(x+1)-1/x=3-2 (2x-x-1)/x(x+1)=1 x-1=x(x+1)
x²+x-x+1=0 x²+1=0 ecuatia nu are solutii reale
