Complete Radical

Joe Healy · 2008-03-12 21:23:50

Hi im doing yr 11 advanced maths and im not very good at it:/

Need to get better soon so heres what I need to know test is tommorow so its really too late but eh.

Express 4√2 as a complete radical. Got no I know the answer is √32 but that only from trial and error. Please give me the formula!!

Simplify √54x ÷ √6

Ive decided im gonna fail this test but please for the next one this could be helpful

John E. Franklin · 2008-03-12 22:14:18

You put the twin pieces together.

3 is the same as √3√3, and

that's the same as √(3 times 3), and

that's the same as √9.

Try 5.
√5 times √5, and
that's the same as √25.

Try double that.
Try 10.
√5 tmz √5 tmz √2 tmz √2 is ten.
That means √25 tmz √4 is ten.
And means √50 tmz √2 is ten.

John E. Franklin · 2008-03-12 22:19:29

Now √64 means √16 tmz √4,

so half of that is √64 divided by 2.

But √4 is √2 tmz √2, and

the √2 tmz √2 is the same as 2.

So √x tmz √x is the same as x.

Weird huh?

It's weird because you can't
see it in your head. That's the
problem with hard maths.

mathsyperson · 2008-03-13 08:26:40

The main useful formula you want here is √a x √b = √(ab).

For the first question, you express both terms as square roots and then apply that rule:
4√2 = √16√2 = √32.

The formula works with division too, so you can do that for the second question:
√(54x)/√6 = √(54x/6) = √(9x) = √9√x = 3√x.

Math Is Fun Forum