Posted by **Anonymous** on Tuesday, December 25, 2012 at 3:56pm.

Solve the equation by completing the square.

x^2-2=9x

My answer: x=9/2+or- the sqrt. of 22.25

(but when I checked my answer the actual answer was x=9+or - the sqrt. of 89 and then all over 2)

Please explain why my answer is different from the actual answer.

- Algebra 2 .. -
**Steve**, Tuesday, December 25, 2012 at 4:49pm
x^2 - 9x = 2

x^2 - 9x + (9/2)^2 = 2 + (9/2)^2

(x - 9/2)^2 = 89/4

x = 9/2 ± √(89/4)

x = 9/2 ± √22.25

but you could also factor out the 1/4 in 89/4 and say

x = 9/2 ± √89/√4

x = 9/2 ± √89/2

x = (9 ± √89)/2

these exercises usually want things as fractions rather than decimals, and the quadratic formula usually expresses the answers as they did.

## Answer this Question

## Related Questions

- Algebra 2 .. - Solve the equation by completing the square. 3x^2+4x=1 My answer...
- math,correction - Is this correct now. Problem #1 solve by completing the square...
- math,help,algebra I - I need help can someone help me get unstuck and let me ...
- algebra - can someone tell me if i did the problem correct (solve by completing ...
- Inequality - When I solve the inquality 2x^2 - 6 < 0, I get x < + or - ...
- maht,correction please - Problem #1 Solve by completing the square 2x^2-4x-11=0 ...
- algebra - Simplify: ( sqrt (2) + sqrt (3) ) ( sqrt (2) - sqrt (3) )? a) 2 - 2 ...
- Math - How do you find a square root of a number that's not a perfect square? I'...
- math - determine the area of triangle abc when side ab= square root of x, side ...
- some algebra help (radicals) - I hope I am writing this down right.. I am trying...

More Related Questions