How come x^2 = 25 has 2 solutions but x=root(25) only has one? Aren't they the same thing?

(This is something that I didnt fully understand for quite a while at school.) So when we are solving x2=25, in order to get x "on it's own" we square root both sides. However the definition of root(x) is root(x) = |x| so once we square root our equation we get |x| = |5|, since 5>0 we see |5| = 5 so our equation becomes |x| = 5. From solving modulus equations we know the easiest way to do this is to consider two seperate cases, one case when x >=0 and a second when x<0. This leads to us getting 2 solutions, which are x = -5 or 5. For x=root(25) we dont have to square root both sides so we just end up with x = |5|, again since 5>0, |5| = 5 so x=5. So the second equation (in the queston) has one solution but the first equation has two.

DJ
Answered by Dylan J. Maths tutor

7033 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Integrate the following with respect to x, f(x)=xsin(x)


A curve has the equation y=3x^2-2x+7, find the gradient of the line at the point (6,3)


Given a quadratic equation, how do I find the coordinates of the stationary point?


Find the location and nature of the turning point of the line y=-x^2+3x+2


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning