Question

Solve by using the quadratic formula to solve x2 + 6x = -3.

Answer 1

jonny, hope you have the "quadratic formula" written down for reference somewhere. If not, please write it down now and keep this note handy:\[IF~ax^2+bx+c=0,~then~x=\frac{ -b \pm \sqrt{b^2-4ac}}{ 2a }\]

Answer 2

Here ax^2+bx+c=0 is a quadratic equation, and its solutions can be found through the 2nd formula, the quadratic formula.

Answer 3

Please write x2 + 6x = -3
as\[x^2+6x+3=0.\]

Answer 4

Can you explain why I moved the 3?
Can you explain why I changed your x2 to \[x^2?\]

Answer 5

you moved the 3 to make the equation equal to 0
im not sure why you changed the x2

Answer 6

Right. Your equation MUST be in the form ax^2+bx+c=0, so that you can easily identify the values of a, b and c.

Answer 7

x2 could be ambiguous (confusing); some people would interpret it as \[x _{2},\]whereas others might interpret it as I did, as \[x^2. \]

Answer 8

If you don't want to use equation Editor, you could write "x squared" as x^2.

Answer 9

jonny, look at your \[x^2+6x+3=0\]and compare it to \[ax^2+bx+c=0.\]

Answer 10

Can you now identify the values of a, b and c?

Answer 11

a=?
b=?
c=?
0=0

Answer 12

a=x
b=6
c=3

Answer 13

a=1

Answer 14

Cool!
b=?

Answer 15

b=6

Answer 16

Right on! c=?

Answer 17

c=3

Answer 18

Perfect. So, now, jonny, you need to copy down that quadratic formula\[x=\frac{ -b \pm \sqrt{b^2-4ac}}{ 2a }\]and substitute your values for a, b and c. Bet you've done this before.