Tuesday

July 29, 2014

July 29, 2014

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

X^2 + 9=0

- algebra -
**Reiny**, Monday, October 7, 2013 at 6:56pmIf 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

**Related Questions**

algebra - can someone help me to show how to solve -x+y=3

Algebra - 91. Find the domain of: y=-3x+1 a. all negative numbers b. x>0 c. ...

algebra - an someone show me the steps to solve this problem? x^2 + 5x +8 ...

algebra - Can someone show me how to use the quadratic formula to solve this ...

Pre-Algebra [urgent!] - I can't find the solution to this problem; can someone ...

college algebra - 2/5(5x-3) - 1/3(12x-5). Have the correct answer but need ...

math,algebra - can someone help me create one statement in english representing ...

algebra - can any one show me where to get free online help with algebra? i need...

Algebra - can show me how to do this with out just squaring 3x^(1/2) - x - 6 = 0...

algebra - Can someone show me how to use fractional exponents to solve 5^(1/4)*...