Question

exercitiul 3 va rogg foarte frumoss​

Answer 1

Răspuns:

a) 4x^2+4x-8=0 |:4

x^2+x-2=0

a=1 ;b=1; c= -2

Δ=b^2-4ac =1^2 -4*1*(-2) =1+8 =9

x1 =(-b+√Δ)/2a =(-1+3)/2*1 =2/2 =1

x2 =(-b-√Δ)/2a =(-1-3)/2 = -4/2 = -2

b)(x+3)^2-25=0

(x+3)^2 =25

x+3 =±√25

x+3 =√25 ⇒x+3=5⇒x1=2

x+3= -√25 ⇒x+3 =-5⇒x2= -8

c)x^2+10x+25 =0

(x+5)^2=0

x+5 =0⇒x= -5

d) 3x^2+8x-9=0

a=3 ;b=8; c= -9

Δ=b^2-4ac =8^2-4*3*(-9) =64+108 =172

x1 = (-b+√Δ)/2a =(-8+√172)/2*3 =(-8+2√43)/6

x2 =(-b-√Δ)/2a =(-8-√172)/6 =(-8-2√43)/6

Explicație pas cu pas: