Solving an Equation Containing a Radical, Part 2 of 2, from Thinkwell Precalculus

[ShadyStories]

Wait, how come X-3 becomes (X-3)^2 instead of X^2- 9?

Do you like... group the whole thing beforehand?

Like... hard to explain but do you see it as if there were invisible brackets or something already there?

[Iwantkababnow]

teachers should teach more like this guy!

[tigerclaw3211]

I knew it was 3 in the beggining just by plugging in random numbers

[biggee316]

This seems so contradictory to me, if you square both sides shouldn't it be Xsqr minus 9x = 9 minus Xsqr?

[ThinkwellVids]

@biggee316 Nope, the one side has a square root, by squaring it you are removing the square root on the right side which would leave you with 3-x. The left side isn't xsqr minus 9x because you have to do foil. (x-3)sqr equals more than xsqr-9x. He explains it right on, you gotta remember that equations are a different ball game when squared.

[equilibrium0994]

I WANNA KNOW WHAT HAPPENS WHEN TWO RADICALS ARE IN THE SAME EQUATION D;

[TEHAStin]

wow...i'm impressed by your videos, especially calculus in 20 min...but in my opinion -1 is not a possibility because you have +square root of 1-not a +- square root of 1...in this case, this equation would have had 2 solutions, but now only 3 is solution to this equation.

[darkprincemike]

sir.. im one of your number 1 fan.. you are really smart.. but i thing 2=3+ root 1..... square root 1 is equal 1 but don't forget that -1 can be also the square root of 1.. so that means the two answer are correct and also in the part 1.. I guess.. please check me if im wrong..

[xSandman16x]

I think you're half right, -1 is a possibility but because it does not work for both situations the statement is false.

[lihanou]

i like the sound effect

[Eriknock]

your the man