👤
Cristina2017
a fost răspuns

Efectuati: a) (√5-3x)²-(√5+3x)²+(√5-3x)(√5+3x) b)(√11-√7)(√11+√7)(√5-√3)(√5+√3)

Răspuns :

Hell0
1) (√5-3x)²-(√5+3x)²+(√5-3x)(√5+3x)=
 (√5-3x)²-(√5+3x)² + 5-9x^2=
-12√5x + 5-9x^2 =
-9x^2-12√5x+5=0 /*(-1)
9x^2+12√5x-5=0
 Δ=720+180=900

x1= (-12√5 + √900)/18= (5-2√5)/3
x2= (-12√5 - √900)/18=  (-5-2√5)/3

2) (√11-√7)(√11+√7)(√5-√3)(√5+√3)
(11-7)(5-3)=
4*2=8



 



Alte intrebari