Can you simplify this square root expression without using a calculator?
At first glance, this maths question looks almost impossible to solve, but is it really as difficult as it seems?
In this video, I'll take you through a step-by-step explanation of how to approach this tricky question, simplify the surds, and arrive at the answer.
Whether you're preparing for a maths examination, improving your algebra skills, or simply enjoy solving challenging maths questions, this lesson is for you.
Before watching the solution, try solving the question yourself and share your answer in the comment section. I'd love to know how you approached it.
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Remember, no maths question is impossible when you understand the right approach.
the denominator tells you exactly what
What to do next? Welcome back to my channel, so because the
the denominator is a sword, right? That means I need
to rationalize this first, so let's rationalize
rationalize now to do that we need
to write this as the square root
64 divided by 8 plus 63
They are going to multiply the numerator.
and multiply both the numerator and the denominator by the conjugate of our denominator
and the conjugate of this is 8 minus square root of 63, 8 minus square root of 63.
Now, if we move forward, we can now write this as the square root.
of 64 brackets
8 minus root 63
divided by
8 plus root 63 multiplied by 8 minus root 63 now
if you look at the denominator
it is in the form a plus b multiplied
a minus b means that we can express this as what
a squared minus b squared: difference of two squares
so that's exactly what we are going to
So we will write this as
The Scare Root
of 64 brackets 8 minus root
63 divided by 8 squared minus
63 square if this is the first time you've seen
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So moving forward,
we can now write this as the square root of 64 brackets,
8 minus 63, divided by, now we have 8 squared is 64, minus.
Now the square cancels the square roots, and we have 63.
That means we have reduced this to the square root.
of 64 brackets 8 minus root 63 right
because this becomes one
Okay, now recall that recall.
the square root of a multiplied by p can
can be expressed as the square root of a multiplied by
the square root of b
that we can write this as a square root
64 multiplied by square root of
8 minus the square root of 63, so if we
Then this becomes 8 brackets
the square root
8 minus the square root of 63
and we can go ahead right
and say that this is equal
to 8 square root of
Now we are going to write this as 1 multiplied by what?
8 minus root 63, we have not changed everything
anything divided by one is one over one
We haven't changed anything, and we can write this as eight fruits.
Then we can change one to two.
eight times the square root of 63 divided by two
because when it divides itself we have
one we haven't changed anything yet either
You're going to see why I'm doing this.
Yes. So, stay put and see why. I'm going to explain later.
So, solving this, let's expand the parentheses.
We have 8 times the square root of 2 times 8.
Is 16 minus 2 times the square root of 63 divided by 2?
If we solve for that, we can write this as 8 square root of
Now 16 is the same as 9 plus 7, right, like I said you
you are going to see why I introduced these two
Okay, so 16 is 9 plus 7 multiplied by 2 roots.
and 63 is 9 times 7
so 9 times 7 divided by 2, have you
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We can write this as eight roots now nine can
can be expressed as three squared, right
three squared plus seven can be written as square root
seven squared square root of seven squared
then we have multiplied by, is that supposed to
to be subtraction, sorry, not multiplication by
So minus
root 9 times root 7, right?
Now, everything divided by 2.
Let me come to this side.
Now, we can write this as 8 square root.
3 squared plus square root
7 squared minus 2 multiplied by,
The square root of 9 is 3, multiplied by the square root of 7, now divided by 2.
This is where I explain why I did what I did.
This is the reason.
Remember that a squared
plus b squared minus two a b is the same thing
(a minus b) squared, right, and you can see that
I have arranged this numerator in this form whereby
My a is three and my b is seven, right?
Therefore, let's go ahead and write.
our new simplified equation, so this becomes eight
So, this becomes 3 minus root 7.
all squared divided by 2, okay?
Excuse me.
This is equal to 8.
Then I can write this as the square root of 3 minus
7 divided by the square root of 8
Sorry, the square root of 2 rather.
And here, this, and this—so we have eight.
three minus the square root of seven, divided by the square root of two
Now remember that we cannot leave this root two
No, so we need to rationalize the denominator.
by multiplying the numerator
and multiply the denominator by this, so we have multiplied by root two
multiplied by root two, okay, so now we have eight root two
Bracket 3 minus root 7 divided
Root 2 times root 2 is 2.
If we divide this,
We have 4 root 2 times (3 minus root 7).
If we expand this further, we can write it as 4 times the square root of 2 multiplied by 3.
is 3 root 2 minus root 7 times root 2.
What do we give ourselves? Root 14.
And that's the answer. Thank you for watching.
See you in my next video, bye.