Question 145132
To take the square root of a number, you need to answer the question: What other number when multiplied by itself gives you the original number.


So what number multiplied by itself gives you {{{y^2}}}?  Well, we know that {{{y^2=y*y}}}, so there is part of the answer to that part, namely: {{{sqrt(y^2)=y}}}.  You also have to consider that {{{y^2=(-y)(-y)}}} also.  So {{{sqrt(y^2)=y}}} OR {{{sqrt(y^2)=-y}}}.


Apply this same logic to the number 16.  What number, multiplied by itself, makes 16?  Remember that {{{4*4=16}}} and {{{-4*-4=16}}}.


So now we have:  {{{y=4}}} or {{{y=-4}}} (You can also say {{{-y=4}}} or {{{-y=-4}}}, but those are just equivalent expressions to the ones already given.)


Do the other problem the same way.  You'll get {{{x-3}}} equal to plus or minus something, so you will need to solve each of those resulting equations by adding 3 to both sides.