Answer
$y^{2} +7y+12$
Work Step by Step
$(y+3)(y+4)$
1. Multiply the first terms of each bracket together. $(y)(y) =y^{2}$
2. Multiply the outermost terms of each bracket together. $(y)(4) = 4y$
3. Multiply the innermost terms of each bracket together. $(3)(y) = 3y$
4. Multiply the last terms of each bracket together. $(3)(4) = 12$
5. Add all answers from steps 1-4 to get $y^{2} +4y+3y+12$.
6. Collect like terms to get $y^{2} +7y+12$.