(1) $4x^2 + 4xy + y^2 =$

(2) $x^2 + 18xy + 81y^2 =$

(3) $4x^2y^2 + 20xy + 25 =$

(4) $16 + 24y + 9y^2 =$

(5) $4x^2 + 2x + 1/4 =$

(6) $9x^2 + 2/3x + 1/81 =$

(7) $121 + 22a + a^2 =$

(8) $x^2 + 12x + 36 =$

(9) $4x^2 + 28x + 49 =$

(10) $a^2 + 18a + 81 =$

(11) $81x^2 + 18xy + y^2 =$

(12) $m^2 + m + 1/4 =$

(13) $9x^2 + 30x + 25 =$

(14) $x^2 + 4x + 4 =$

(15) $25x^2 + 10x + 1 =$

(16) $9x^2 + 24x + 16 =$

(17) $27x^2 + 18xy + 3y^2 =$

(18) $x^4 + 6x^2y + 9y^2 =$

(19) $100 + 120b + 36b^2 =$

(20) $a^2x^4 + 18a^2x^2 + 81a =$