Margföldun – Æfing 3.2 – Lausnir

  1. qn+5r2+m
  2. qnr2·q5·rm = qn+5r2+m
  3. (2a + 4b)2 = 4a + 2·8ab + 16b2 = 4a + 16ab + 16b2 (notum ferningsreglu)
  4. (3x – 5)2 = 9x2 – 2·(-15x) + 25 = 9x2 + 30x + 25 (notum ferningsreglu)
  5. (6q + 2)(6q – 2) = 6q2 – 4 (notum ferningsreglu)
  6. a(x + 3) = ax + 3a
  7. (x2 – b – 1)2x = 2x3 – 2bx – 2x
  8. (2 – x)(x + 1) = 2x + 2 – x2 – x = x – x2 + 2
  9. (p + q + r)(p + q – r) = p2 + pq – pr + pq + q2 – qr + rp + rq – r2 = p2 + 2pq + q2– r2