Posted by **jessica** on Sunday, September 5, 2010 at 11:16am.

(a minus sqrtx)^2=25

I have no idea of how to work this problem where i in up with the answers of a=7,-3. Basiclly I just gave it a guess. Could someone show the steps I need to take. Thanks.

- algebra -
**bobpursley**, Sunday, September 5, 2010 at 11:34am
take the sqrt of each side.

a-sqrtx=+- 5

now work each possible sign

sqrtx=a-5 or sqrt x=a+5

then square each side:

x=(a-5)^2 or x=(a+5)^2

Now you are presented with a quandry, resolve this way. If the domain of x is restricted to real numbers, then you cant take a sqrt of a negative numer, so

x>= 0 which means

(a-5)>0 or a>5 and (a+5)>0 a>-5 but the first predominates, so a>5 is the restriction on a.

- algebra -
**Trina**, Sunday, September 5, 2010 at 12:04pm
what happen the the results of a=7, -3 to this problem because when I plug them in it equal to 25 in the end. Could you explain this a little more for me. Thanks.

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