Question

9x^2-6x-3=0 ;x^2+10x=24 ;25x^2-10x-8=0 cu formule de calcul prescurtat sau x^2=a

Answer 1

9x²-9x+3x-3=0⇒ 9x(x-1) + 3(x-1) = (x-1)(9x-3)=0 ⇒ 3(x-1)(3x-1)=0
x-1=0⇒ x=1 sau 3x-1=0⇒ x=1/3⇒ x∈{1;1/3}

x²+12x-2x-24=0⇒ x(x+12) -2(x+12) =0 ⇒  (x-2)(x+12)=0
x-2=0⇒ x=2 sau x+12=0⇒ x=-12⇒ x∈{2;-12}

25x² -20x+10x-8=0⇒ 5x(5x-4) +2(5x-4)=0⇒ (5x-4)(5x+2)=0
5x-4=0⇒ x=4/5 sau 5x+2=0⇒ x=-2/5 ⇒ x∈{-2/5 ; 4/5}