Question

Afla nr natural X care verifica egalitatea : 3*16=X*(X+2)


VA ROG ! (explicati daca puteti)

Answer 1

3*16=x*(x+2)
48=x*(x+2)
48=x²+2x
48-x²-2x=0
-x²-2x+48=0
x²+2x-48=0
x=-2+-√2²-4*1*(-48)/2*1
x=-2+-√2²-4*(-48)/2*1
x=-2+-√4-4*9-48)/2*1
x=-2+-√4+192/2
x=-2+-√196/2
x=-2+-14/2
x=-2+14/2
x=-2-14/2
x=6
x=-8

deci solutia ecuatiei x=6  (  numar natural ) 

Answer 2

3 x 16 = x (x + 2) 
48 = x² + 2x 
x² + 2x = 48 
x² + 2x - 48 = 0 
Δ = b² - 4ac = 4 +192 = 196 
x1,2 = (-b +-√Δ) / 2a 

x1 = (-2 + 14)/2 = 12/2 = 6  
x2 = (-2 - 14)/2 = - 16/2 = -8

numere naturale = > numere pozitive , deci x = 6