Выделите квадрат двучлена в таких тричленах: 1) а^2+6а+13 2) х^2+8х+21 3) х^2-10х+27 4) х^2-2х+2 5) 36^2+85х+50 6) 4х^2+15-12х

1) а^2 +6а +13 = а^2 +2*3а +9 +4 = (a+3)^2 +4
2) х^2 +8х +21 = x^2 +2*4x +16 +5 = (x+4)^2 +5
3) х^2 -10х +27 = x^2 -2*5x +25 +2 = (x-5)^2 +2 
4) х^2 -2х +2 = x^2 -2*1x +1 +1 = (x-1)^2 +1
5) 36^2 +85х +50 = (6x)^2 +2*7*6x +49 +x +1 = (6x+7)^2 +x +1
6) 4х^2 +15 -12х = (2x)^2 -2*3*2x +9 +6 = (2x-3)^2 +6