Question

Domeniul maxim de definitie :
a) f(x)=log10 din (5x²+3x-8)

b). f(x) = log 3/7 din x-x²

Answer 1

a)
10>0 si 10≠1 , deci baza exista
5x²+3x-8>0
x1,2=(-3+-√(9+160))/2*5=(-3+-13)/10
x1=-16/10=-8/5
x2=10/10=1
x∈(-∞;-8/5)∪(1;∞)


b) 3/7>0 si 3/7≠1, deci baza exista
x-x²>0
-x²+x>0
x1=0
x2=1
x∈(0;1)
as simple as that!!