Question

descompunerii în factori

Answer 1

$24) {x}^{2} + x - 6$

$= {x}^{2} + 3x - 2x - 6$

$= x(x + 3) - 2(x + 3)$

$= (x + 3)(x - 2)$

$25) {x}^{2} + 4x - 12$

$= {x}^{2} + 6x - 2x - 12$

$= x(x + 6) - 2(x + 6)$

$= (x + 6)(x - 2)$

$26) {x}^{2} - 6x - 7$

$= {x}^{2} - 7x + x - 7$

$= x(x - 7) + x - 7$

$= (x - 7)(x + 1)$

$27) {x}^{2} - 11x - 12$

$= {x}^{2} - 12x + x - 12$

$= x(x - 12) + x - 12$

$= (x - 12)(x + 1)$

Answer 2

ax^2 +bx +c =0
S=x1+x2 = - b/a
P=x1*x2 = c/a, cf formulelor lui Vièt.
ax^2 + bx + c = a(x-x1)(x-x2)
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24) S= -1, P= -6 , x1= -3, x2=2
x^2 + x - 6 = (x+3)(x-2)

25) S= -4, P = -12 ⇒ x1= -6, x2= 2
= (x+6)(x-2)

26. S=6, P= -7 ⇒ x1=7, x2= -1
= (x-7)(x+1)

27. S=11, P= -12 ⇒ x1= 12, x2= -1
= (x-12)(x+1).