Răspuns:
x € Q
-5x+11=-3x(x+15)
-5x+11= - 3x^2- 45x
3x^2+45x-5x+11=0
3x^2+40x+11=0
Folosim
x=[ - b +/- rad( b^2-4ac)] /2a
x= [- 40+/- rad (40^2- 4×3×11)] /(2 ×3)
x=[ - 40 +/- rad (1600-132)]/6
x=[ - 40 +/- rad 1468]/6
x=[ - 40 +/- 2(rad 367)]/6
x 1 =[ - 40 - 2(rad 367)]/6
x 1 = 2[ (- 20- rad 367)/6]
x 1 =( - 20-rad 367)/3
x 2 = [ - 40 + 2(rad 367)]/6
x 2 = 2[( - 20+ rad 367)]/6
x 2 = (- 20+ rad 367) /3
Explicație pas cu pas: