а) x^2+8x+31=х^2+2*4*x+4^2-4^2+31=х^2+2*4*x+16+15=(x+4)^2+15
b) 25a^2-20a+10 = (5a)^2-2*5a*2+2^2-2^2+10 =(5a-2)^2+6
а) x^2+8x+31=х^2+2*4*x+4^2-4^2+31=х^2+2*4*x+16+15=(x+4)^2+15
b) 25a^2-20a+10 = (5a)^2-2*5a*2+2^2-2^2+10 =(5a-2)^2+6