Answers

2014-03-13T14:28:02+08:00
X² + 7 × -66 = 0
x² = -7 × +66
x² = -462
 \sqrt{x²} (or square root of x²) =  \sqrt{-462}
x =  \sqrt{-462}
0
I think this is incomplete :)
You can't combine terms with dissimilar variable and exponent. Constant to number with variable and exponent isn't compatible.
then just delete this