The given expression is
![(x+4)(3x^2 +2x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/rcrgj3dio4zg1cmeo1qqu2q1t47n6245mi.png)
And in the second factor, x is common. So on taking x out, we will get
![(x+4)(x)(3x+2) = x(x+4)(3x+2)](https://img.qammunity.org/2019/formulas/mathematics/high-school/s1ii0f4du9mtvmbldonl2t0lbphuvlxb4d.png)
We can expand it by distributing , that is
![(x+4)(3x^2 +2x) = x(3x^2 +2x) +4 (3x^2 +2x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/q8gro5gio34f8vkit2utczhke8fmrm1mol.png)
![= 3x^3 +2x^2 + 12x^2 +8x](https://img.qammunity.org/2019/formulas/mathematics/high-school/bwavln3oae91yt1z9rjwluql0xgex9pz4d.png)
Combining like terms,
![= 3x^3 +14x^2 +8x](https://img.qammunity.org/2019/formulas/mathematics/high-school/gqny3luum69iuu4hxf1zru6riif65euwgc.png)
And that's the expanded form ., and the given expression can also be written in that way .