Răspuns:
Explicație pas cu pas:
2x²-7x-4=0
x1,2=(7±√49+32)/4=(7±9)/2 ⇒x1=7+9/4=16/4=4 x2=7-9/4=-1/2
2x²-7x-4=(2x+1)(x-4)
x₁ = 4
x₂ = - 1/2
2x ² - 7x - 4 = 0
2x² + x - 8x - 4 = 0\
x(2x + 1) - 4(2x + 1) = 0
(x - 4)(2x + 1) = 0
x - 4 = 0 ⇒ x₁ = 4
2x + 1 = 0 ⇒ x₂ = - 1/2
