When you have problem like this you have to figure out what two numbers ADD to 11 and multiply to 30??? 15 and 2 multiply to 30....but they do not ADD to 11
10 and 3 ? Nope
6 and 5 ? YES!
SO you can FACTOR it out to look like this
x^2+11x+30 = (x+5)(x+6)
If you multiply it out you will find it is correct! G'luck!
