Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

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I did it! The quintic equation has only one real root (i.e 4 complex roots and 1 real root).

Seriously, you shouldn't have to deal with a nasty equation like that at A-level or equivalent.

Original post by TenOfThem

This is not correct either as

(b^4)^2 \not = b^5

You have an odd and even power so it's impossible to use a substitution right?

OP

Original post by Dr A

I did it! The quintic equation has only one real root (i.e 4 complex roots and 1 real root).

Seriously, you shouldn't have to deal with a nasty equation like that at A-level or equivalent.

What does it mean?

Original post by Dr A

I did it! The quintic equation has only one real root (i.e 4 complex roots and 1 real root).

Seriously, you shouldn't have to deal with a nasty equation like that at A-level or equivalent.

I checked on Wolfram (equation solver) and it has 3 real roots.

It's actually simple. Set both of the products equal to

0.075

and solve separately

b=-0.255....

is the only solution but don't bother working it out.

OP

The answer given by the teacher is around 0.27...

Original post by Madalaine M

I checked on Wolfram (equation solver) and it has 3 real roots.

It's actually simple. Set both of the products equal to

0.075

and solve separately

You're right. I misread it and forgot to include solutions. I think I should go to bed lol

(edited 11 years ago)

Original post by cwynter

The answer given by the teacher is around 0.27...

b^2=0.075

b=+/- \sqrt{0.075}

And

\sqrt{1.2-\frac{b}{2}}=0.075

Square both sides:

\frac{9}{1600}=1.2-\frac{b}{2}

-\frac{1911}{1600}=-\frac{b}{2}

b=2.34

Hope that's right!

(edited 11 years ago)

OP

Original post by Madalaine M

b^2=0.075

b=+/- \sqrt{0.075}

And

\sqrt{1.2-\frac{b}{2}}=0.075

Square both sides:

\frac{9}{1600}=1.2-\frac{b}{2}

-\frac{1911}{1600}=-\frac{b}{2}

b=2.34

Hope that's right!

That's brilliant! Thank you so much for you help!!

Original post by cwynter

That's brilliant! Thank you so much for you help!!

They are only approximations. I took 0.075 to equal 0 because it's incredibly small value relative to question. They are correct to 1 decimal place.

(edited 11 years ago)

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