### Video Transcript

Make π the subject of the formula
π equals two πΏ minus π over four.

Well, what Iβm gonna do is actually
demonstrate a couple of methods to actually solving this problem. Okay, so weβve got π equals two πΏ
minus π over four. So first of all, what Iβm gonna do
is actually subtract two πΏ from each side. And when I actually do that, I get
π minus two πΏ is equal to negative π over four.

The next stage is actually to
multiply each side of the equation by four, because obviously we want π to be on
its own. So when we do that, we get four
multiplied by π minus two πΏ is equal to negative π.

So now if we actually look back at
the question, we can see that we want π as the subject of the formula, not negative
π. So therefore, what weβre gonna do
is actually multiply each side of the equation by negative one. So therefore, weβre gonna get
negative four multiplied by π minus two πΏ equals π.

So now if we actually expand the
bracket, first of all weβre gonna get negative four multiplied by π, which gives us
negative four π. And then we have negative four
multiplied by negative two πΏ, which is gonna give us eight πΏ. Thatβs because a negative
multiplied by a negative is a positive. So therefore, we get negative four
π plus eight πΏ is equal to π. And then if we just swapped the
equation around just so we can have π on the left-hand side, we see that π is
equal to negative four π plus eight πΏ. So weβve made π the subject of the
formula.

Okay, great! I said we shall use a couple of
methods. So Iβm just using another method
just to check. So again, weβre gonna start with π
is equal to two πΏ minus π over four. So then the first stage is gonna be
to add π over four, which will give us π plus π over four equals two πΏ. And the reason weβre doing this
with this method is what weβre trying to do is actually avoid having a negative π,
cause sometimes some students make mistakes when it comes to having a negative
π.

Then next, what weβre gonna do is
subtract π from each side. So therefore, weβre gonna have π
over four is equal to two πΏ minus π. Then we multiply each side of the
equation by four. And we get π is equal to four
multiplied by two πΏ minus π. And then if we expand the bracket,
we get π is equal to eight πΏ, because we got four multiplied by two πΏ, minus four
π, and thatβs because we have four multiplied by negative π. So therefore, we get that π is
equal to eight πΏ minus four π.

Letβs just rearrange this to have
it in the same form as we had the first way working it out. So therefore, again, we get π is
equal to negative four π plus eight πΏ. So therefore, weβve made π the
subject of the formula and shown you two methods to do so.