Can someone help with this?

Question

0

1663

3

+1452

I think I complete the square but idk Rewrite the expression $4s^2 + 28s + 45$ in the form $(cs + p)^2 + q$. What is $q$?

CPhill · Answer 1 · 2017-10-20T02:23:57

4s^2 + 28s + 45 factor out the 4

4 [ s^2 + 7s + 45/4]

Take (1/2) of 7 = 7/2......square this = 49/4 ....add it and subtract it

4 [ s^2 + 7s + 49/4 + 45/4 - 49/4 ]

Factor the first three terms and simplify

4 [ ( s + 7/2)^2 - 1 ]

4(s + 7/2)^2 - 4

So q = -4

Guest · Answer 2 · 2017-10-20T02:42:59

CPhill: Aren't you actually dividing by 4 in the first step and it should disappear altogether in the 2nd step (outside the bracket)?

CPhill · Answer 3 · 2017-10-20T03:00:29

This would be true if we were setting the equation to 0 and solving

But we aren't solving anything here......we are just completing the square