Let us first find the HCF of all the terms of the given polynomial 3x4+6x3y+9x2 by factoring the terms as follows:
3x4=3×x×x×x×x6x3y=2×3×x×x×x×y9x2=3×3×x×x
Therefore, HCF=3×x×x=3x2
Now, we factor out the HCF from each term of the polynomial 3x4+6x3y+9x2 as shown below:
3x4+6x3y+9x2=3x2(x2+2xy+3)
Hence, 3x4+6x3y+9x2=3x2(x2+2xy+3).