Հանրահաշիվ

131.

ա) (a + 2b)(a^2 — 2ab + 4b^2) = a^3 + 8b^3

բ) (a — b + c) (a + b — c) = a^2 — c^2 + 2bc — b^2

գ) (a + 2b)(a — 2b)(a^2 + 4b^2) =a^4 — 16b^4

138.

ա) 2a + 4b =2 (a + 2b)

բ) ba — b = ab — b

գ) 6x — 2 = 2 (3x — 1)

դ) yx + 2y = xy — 2y

ե) 3a — 12b = 3 (a — 4b)

զ) 7x -28 = 7 (x — 4)

139.

ա) x (a + b) + y (a + b) = ax — bx + ay — by

բ) (a + b) a — b (a+b) = a^2 — 2ab + b^2

գ) m (n — 3) -2 (n — 3) = mn — 3m — 2n + 6

դ) (x — y) 3 — a (x + b) = 3x — 3y — ax — ab

ե) 2a (1- b) — 3 (1 — b) = 2a — 2ab — 3 + 3b

զ) a (b + 3) — b (3 + b) = ab + 3a — 3b — b^2