Use the quadratic formula to solve the equation. If necessary, round to the nearest hundredth.

x² – 21 = –4x
• 7, 3
• –7, 3
• 7, –3
• –7, –3

4 answers

put it into standard form of a quadratic ...

x^2 + 4x - 21 = 0
how nice that it factors ....

(x+7)(x-3) = 0

so x = ... or x = ....
But you wanted to use the formula ...

x = (-4 ± √100)/2
= (-4 ± 10)/2
= (-4+10)/2 or (-4-10)/2
= .....
h^2-2h-2=0
it’s -7,3