Expanding Quadratics

Work this out:
(y+4)(y-7)(y+6)= (?)
and if you are really smart, factorise:
y3 - 54= (?)

(y+4)(y-7)(y+6)= 0
for the value of y I chose.

Is that what you were looking for?

Originally posted by Knight Square
Work this out:
(y+4)(y-7)(y+6)= (?)
and if you are really smart, factorise:
y3 - 54= (?)

y^3+3y^2-46y-168 = ?

Right?

Do we really need endless topics covering basic math?

you probably meant y³ - 64 = ?

but curiously enough (3.77976314968462)³= 54

Originally posted by XanthosNZ
Do we really need endless topics covering basic math?

How else will homework be completed?

Originally posted by XanthosNZ
Do we really need endless topics covering basic math?

XanthosNZ is a kiwi just like me and us NZders do get Homework right?

Originally posted by Knight Square
Work this out:
(y+4)(y-7)(y+6)= (?)
and if you are really smart, factorise:
y3 - 54= (?)

Expand this:
(y+4)(y-7)(y+6)
and if you are really smart, evalute:
y3 = 64, what does y =

Originally posted by AThousandYoung
y^3+3y^2-46y-168 = ?

Right?

Incorrect, I did get confuse with the '^', what does it mean? and I believe that is not needed for this. (I think)😕

Originally posted by Knight Square
XanthosNZ is a kiwi just like me and us NZders do get Homework right?

I do get homework. But I do it myself and even if I were to ask for help here I doubt most of you could manage to say anything useful.

Also, AThousandYoung is right. Hope you fail.

Originally posted by XanthosNZ
I do get homework. But I do it myself and even if I were to ask for help here I doubt most of you could manage to say anything useful.

Also, AThousandYoung is right. Hope you fail.

What, you think this was my homework, now. XanthousNZ that is just for fun. And I am only 4th Form and this is 6th Form Maths, Level 2 XanthousNZ Level2.

Originally posted by Knight Square
Incorrect, I did get confuse with the '^', what does it mean? and I believe that is not needed for this. (I think)😕

The ^ means that the next number is superscripted; exponents are superscripted.

Originally posted by Knight Square
Work this out:
(y+4)(y-7)(y+6)= (?)
and if you are really smart, factorise:
y3 - 54= (?)

One interesting pattern to note that may be helpful for quick calculations in the future:

(x+A)(x+B) = x^2 + (A+B)x + AB

(x+A)(x+B)(x+C) = x^3 + (A+B+C)x^2 + (AB+AC+AB)x + ABC

(x+A)(x+B)(x+C)(x+D) = x^4 + (A+B+C+D)x^3 + (AB+AC+AD+BC+BD+CD)x^2 + (ABC+ABD+ACD+BCD)x + ABCD

etc...

This pattern arises from the combinatoric process of selecting "n" x's and "m-n" constants from the factorization of a polynomial of degree "m". It's handy to remember, because it saves you making mechanical errors keeping track of all the x^2 and such.

Originally posted by Knight Square
Work this out:
(y+4)(y-7)(y+6)= (?)
and if you are really smart, factorise:
y3 - 54= (?)

If you want a quick estimate of Y3-54=?

just take the square root of 54 and divide by 2. The answer is usually accurate to 1 or 2 decimal places with small numbers like 54....3.67 in this case

EDIT: welcome back PB6

Originally posted by uzless
If you want a quick estimate of Y3-54=?

just take the square root of 54 and divide by 2. The answer is usually accurate to 1 or 2 decimal places with small numbers like 54....3.67 in this case

EDIT: welcome back PB6

Good to be back! But I'm still going to lurk for a while. I just hate people in general, so I'm ramping up to full-blown posting.