[tex]a)\,x^2-6x+9=(x-3)^2\\b)\,x^2-8x+16=(x-4)^2\\c)\,x^2-10x+25=(x-5)^2\\d)\,x^2-12x+36=(x-6)^2\\e)\,16x^2-8x+1=(4x-1)^2\\f)\,25x^2-10x+1=(5x-1)^2\\g)\,25x^2-20x+4=(5x-2)^2\\h)\,25x^2-60x+36=(5x-6)^2\\i)\,4x^2-28x+49=(2x-7)^2\\j)\,25-70x+49x^2=(5-7x)^2[/tex]
