1. Factoring out the GCF:
[tex]=4(x^2+5x+4)[/tex]2. Rewrite the second term in parentheses as a difference (find two numbers that added equals 5 and multiplied 4):
[tex]=4(x^2+4x+x+4)[/tex]3. Factor by grouping:
[tex]=4(x(x+4)+(x+4))[/tex][tex]=4(x+4)(x+1)[/tex]