Câu trả lời:
a)x\(^4\)+2x\(^{^{ }3}\)+x\(^2\)
=x\(^2\)(x\(^2\)+2x+1\(^2\))
=x\(^2\)(x+1)\(^2\)
b)x\(^2\)-7x+12
=(x\(^2\)-2x3,5+3,5\(^2\))-0,25
=(x+3,5)\(^2\)-0,25
c)x\(^2\)-5x-14
=-(x\(^2\)+2x2,5+2,5\(^2\))+7,75
=-(x+2,5)\(^2\)+7,75
d)4x\(^2\)-3x-1
=-((2x)\(^2\)+22x1+1\(^2\))-1
=-(2x+1)\(^2\)-1