Oblicz 22tysia: log₂ (x² + 6x+17)=3 log x − log(x+90)= −1

Eta: 1/ dziedzina: x² +6x +17 >0 ,Δ<0 => D= R i teraz z def. logarytmu x²+6x+17= 2³ => x²+6x +9=0 => ( x +3)²=0 => x= − 3 2/ D: x>0 i x+90>0 => x >0

	a
loga− logb= log
	b

to

	x
log		= −1
	x+90

i z def. log

	x		1		1
		=		, bo 10−1=
	x+90		10		10

dokończ .......