I used both methods on the same equation, but I got different answers. The one on the left is the quadratic equation while the one on the right is completing the square. Can anyone spot my mistake? Thanks!
I used both methods on the same equation, but I got different answers. The one on the left is the quadratic equation while the one on the right is completing the square. Can anyone spot my mistake? Thanks!
in the quadratic formula version you forget to divide sqrt(-48) by 4
in the completing the square version you divide the 8 by 2 properly but then it shows up again as 8 inside the parens.
slow down and redo both carefully
No it doesn't.
$\displaystyle \begin{align*} 2 \left( x^2 + 2x + 1 - 1 + 4 \right) &= 2 \left[ \left( x + 1 \right) ^2 + 3 \right] \\ &= 2\left( x + 1 \right) ^2 + 6 \end{align*}$
not $\displaystyle \begin{align*} 2 \left( x + 1 \right) ^2 + 3 \end{align*}$