***2015 LC Maths Paper 1 - Higher Level - June 5th***

MmmPancakes

randylonghorn wrote: »

Ignore all the commentators, in the media or on here, for the moment. By all means go back and read them after the dust has settled if you wish; you're not drones and it is "relevant to your interests" as the old meme had it.

For now, though, it's nothing but a distraction.

You have one task on hand: to calmly go forth and whip the LC's spotty ass, and make it your bi-atch.

I am going to destroy paper 2 tomorrow regardless :cool:

mayway

What's the answer to Question 5, part a)

mayway

Or is it as simple as

x = sqrt (x +6)
=> x^2 = x+6
=> x^2 -x -6 = 0
=>(x-3)(x+2) = 0
=> x = 3, -2

?

SteveZissou

mayway wrote: »

Or is it as simple as

x = sqrt (x +6)
=> x^2 = x+6
=> x^2 -x -6 = 0
=>(x-3)(x+2) = 0
=> x = 3, -2

?

Fairly sure that's what I did, seemed too simple though! But I think they asked that question as a sort-of intro to the similar two parts that followed - differentiating and finding the turning points

Kremin

mayway wrote: »

Or is it as simple as

x = sqrt (x +6)
=> x^2 = x+6
=> x^2 -x -6 = 0
=>(x-3)(x+2) = 0
=> x = 3, -2

?

Yes except -2 isnt actually a solution, if you put it into the original you get -2=root-2+6
-2=2 which isnt correct. X can't be -

SteveZissou

Kremin wrote: »

Yes except -2 isnt actually a solution, if you put it into the original you get -2=root-2+6
-2=2 which isnt correct. X can't be -

But root four can equal -2, no? (-2)^2 is four

Kremin

SteveZissou wrote: »

But root four can equal -2, no? (-2)^2 is four

No
just look at the original equation
x=rootx+6

if x=-2
-2=root4
-2=2
which isn't true, therefore -2 cannot be a solution

SteveZissou

Kremin wrote: »

No
just look at the original equation
x=rootx+6

if x=-2
-2=root4
-2=2
which isn't true, therefore -2 cannot be a solution

Our teacher always said a root can be the negative form of the number... this is what it says on Wikipedia: "In mathematics, a square root of a number a is a number y such that y^2 = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a. For example, 4 and −4 are square roots of 16 because 4^2 = (−4)^2 = 16."

2 is no more a square root than -2, it's only in practical applications that we opt for the positive value i.e. distance, mass, height

qweerty

SteveZissou wrote: »

Our teacher always said a root can be the negative form of the number... this is what it says on Wikipedia: "In mathematics, a square root of a number a is a number y such that y^2 = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a. For example, 4 and −4 are square roots of 16 because 4^2 = (−4)^2 = 16."

2 is no more a square root than -2, it's only in practical applications that we opt for the positive value i.e. distance, mass, height

Not wishing to trample on Kremin's feet, but...

If only for the fact that the square root symbol denotes the non-negative (or principal) square root, the answer can only be x = 2.

x^2 = 4 >> x = +/- 2

But...Sqrt(4) = x >> x = 2

Luke Armstrong

SteveZissou wrote: »

Our teacher always said a root can be the negative form of the number... this is what it says on Wikipedia: "In mathematics, a square root of a number a is a number y such that y^2 = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a. For example, 4 and −4 are square roots of 16 because 4^2 = (−4)^2 = 16."

2 is no more a square root than -2, it's only in practical applications that we opt for the positive value i.e. distance, mass, height

Put it this way, if the square root was both the positive and negative values, why would there be any need for the + or - in the -b formula

Kremin

SteveZissou wrote: »

Our teacher always said a root can be the negative form of the number... this is what it says on Wikipedia: "In mathematics, a square root of a number a is a number y such that y^2 = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a. For example, 4 and −4 are square roots of 16 because 4^2 = (−4)^2 = 16."

2 is no more a square root than -2, it's only in practical applications that we opt for the positive value i.e. distance, mass, height

If you root-4 was 2 then there would be no need for complex numbers....

when you find values for x you're always supposed to test them and see if they work because when you square any equation it creates fake solutions.
When you get the square root of a number you're asking yourself, what multiplied by itself gives that number? so when you say root -4, what multiplies by itself to give -4... and the answer is nothing (real anyway)
-2 x -2 = 4 (double negative)
2x2 = 4 which is positive


put root -4 on a calculator and i guarantee it will say math error, because it's impossible without bringing in complex numbers.

And regardless of this, substituting -2 for x into the original equation gives LHS: -2 Rhs: 2.
It's not right.