Note:
that is your mistake.
Also, (a+b)^2 =
the problem is . This becomes . I multiplied both sides by to get , then added to each side to get , divided both sides by 4.055 to get and took the square root of both sides to get x=.004965 or . My book however says the answer is so what have I done wrong? This is actually a chemistry problem so 4.9 to 4.4 is a bigger difference than I am comfortable with.