Բ)

{x + y = 7 = > {x = 7 — y = > {x = 7 — y = > {x = 7 — y (1)
{xy = 12 = > {(7 * y) * y = 12 = > {7y — y₂ = 12 = > {-y² + 7y — 12 = 0

-y2 + 7y — 12 = 0

D = -b — 4ac = 49 — 4 * 1 *(-12) = 1

[y = -7 — 1/-2 = 4 => {[x = 7 — y [{x = 7 — y [{x = 3
[y = -7 + 1/-2 = 3 => {[y = 4 = > [{y = 4 [{y = 4
{[y = 3 [{y = 3 = > [{x = 4
[{x = 7 — y [{y = 3
[{y = 3

Պատ․` (3;4)(4;3)

Գ)

{x + y = 3 = > {x = 3 — y = > {x = 3 — y = > {x = 3 — y (1)
{xy = -28 = > {(3 — y) * y = -28 = > {3y — y₂ = -28 = > {3y — y² +28 = 0

3y — y² +28 = 0

D = -b — 4ac = 9 — 4 * (-1) * 28 = 121

[y = -3 — 11/-2 = 7 => {[x = 3 — y [{x = 3 — y [{x = -4
[y = -3 + 11/-2 = -4 => {[y = 7 = > [{y = 7 [{y = 7
{[y = -4 [{x = 3-y = > [{x = 7
[{y = -4 [{y = -4

Պատ․՝ (-4;7)(7;-4)