Răspuns:
Explicație pas cu pas:
a) x-5=4² x-5=16 x=16+5=21
b)x³+x²+4x-5=x³ x²+4x-5=0 (x-1)(x+5)=0 x1=1 x2=-5
c)7^(5x-3)=7² 5x-3=2 5x=5 x=1
d)2^2x+5×2^x+6=0 notam 2^x=t
t²+5t+6=0 (t+2)(t+3)=0 t1=-2; t2=-3 2^x=-2 ecuatia exponentiala nu are solutii
e)6x+12=2 6x+12>0 x>-2
6x=-10 x=-5/3>-2
f)(x+1)(x+2)=2² x∈(-∞,-2)∪(-1,∞)
x²+3x+2=4 x²+3x-2=0 x1,2=-3±√9+8/2=-3±√17/2
√17≅4,12 x1=-3+√17/2=-1,12/2 nu se afla in domeniul de definitie
x2=-3-4,12/2=-3,56
