Hi, 1.4y^4+9=13y^2 (Let x = y^2) ⇒ 4x^2 -13x + 9 ⇒ (4x-9)(x-1) ⇒ x = 9/4, x = 1 y^2 = 9/4, y = ± 3/2 OR y^2 = 1, y = ± 1 2.x-3x ^1/2+2=0 (s = x^2)⇒ s^2-3s + 2 = 0 ⇒ (s-2)(s-1) = 0 ⇒ s = 2, s = 1 x = ± sqrt(s), x = ± sqrt(2), x = ± 1 etc