5x^3+35x^2+5x+35=?

You can do this by grouping as follows:

(5x^{3} + 35x^{2}) + (5x + 35) Grouping.

5x^{2}(x + 7) + 5(x+7) Factoring each part by use of the distributive property.

(5x^{2} + 5)(x + 7) Factoring further.

5(x^{2 }+ 1)(x + 7) You can pull out a 5.