Posted by **tammi** on Monday, October 7, 2013 at 6:03pm.

can someone show me how to solve this the instructions are for me to solve by the quadriatic formula is this really 8 grade math im confused im trying to help my daughter tammi and i have never run across this before

X^2 + 9=0

- algebra -
**Reiny**, Monday, October 7, 2013 at 6:56pm
If the instructions are to solve by the quadratic formula, then this topic could be in grade 8 depending in what country you live.

for any equation of the form

ax^2 + bx + c = 0,

x = (-b ± √(b^2-4ac) )/(2a)

for your x^2 +9 = 0

a = 1, b = 0 , and c = 9

x = (0 ± √(0-36)/2

= ± √-36/2

= 3i , where i = √-1 , if she has studied complex numbers

or

there is no solution in the set of real numbers since we cannot take the square root of a negative number

could be done without the formula.....

x^2 + 9 = 0

x^2 = -9

x = ± √-9 = ± 3i as before

## Answer this Question

## Related Questions

- algebra - please help im lost the instructions are to solve by using thee ...
- math - solve by the quadriatic formula, Im still trying to figure how to do this...
- Algebra - I am trying to solve the following using the Quadratic Formula but I ...
- Math - Solve for S: r^2s-5s=7. Solve for b: L= 4a^2b. I'm confused about how to ...
- math - can someone show me how to do these problems? Please? I really don't know...
- math - can someone show me how to do these problems? Please? I really don't ...
- Math - solve for y 3x + y = 2 Trying to help out my daughter, if you could show ...
- Algebra 2 - Solve each system 3x+2y= -2 9x- y= -6 I know how to solve for x but ...
- Math - I am trying to figure how to solve this but I am totally confused? Can ...
- algebra - Solve by elimination method. 2r-5s=-33 5r+2s=48 Solve by substitution ...

More Related Questions