x2y2 2F3 x + y2 k + 1 x + y 2 k + 1 a b/2 a0 + 1 a1 + 1 a2 + 1 a3 + 1 a4 a0 + 1 a1 + 1 a2 + 1 a3 + 1 a4 n k/2 p 2 x2pp − 2 − 1 1 − x 1 1 − x2 ∑ 0 ≤ i ≤ m 0 < j < n P(i , j) x2y p ∑ i = 1 q ∑ j = 1 r ∑ k = 1 aijbjkcki 1 + 1 + 1 + 1 + 1 + 1 + 1 + x ∂2 ∂x2 + ∂2 ∂y2 |φ(x + iy)|2 = 0 222x t ∫ 1 dt t ∬ D dxdy f(x) = 1/3if 0 ≤ x ≤ 1 2/3if 3 ≤ x ≤ 4 0elsewhere k times x + ⋯ + x yx2 ∑ p prime f(p) = ∫ t > 1 f(t)dπ(t) { k a's a, … , a , l b's b, … , b k + l elements } a b c d e f g h 0 i j k l det c0 c1 c2 ⋯ cn c1 c2 c3 ⋯ cn + 1 c2 c3 c4 ⋯ cn + 2 ⋮ ⋮ ⋮ ∷ ⋮ cn cn + 1 cn + 2 ⋯ c2n > 0 yx2 x3141592 + π xzdcyab y‴3