Maths really hard question gcse

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#1
How do I post the pic of the question
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#2

(Original post by Sxv_)
How do I post the pic of the question
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3 years ago
#3

Divide the entire equation by -2 to get the coefficient of to be 1

so u got

then complete the square of whats inside the

so you got

then multiple the entire expression by 2 to remove the second brackets

from this you can see that the points are
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3 years ago
#4
(Original post by Pretish)

Divide the entire equation by -2 to get the coefficient of to be 1

so u got

then complete the square of whats inside the

so you got

then multiple the entire expression by 2 to remove the second brackets

from this you can see that the points are
That would be wrong I think

You have to multiply by

Then you take the 5.5 over

Divide it by -2

Making the points
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3 years ago
#5
(Original post by Balkaran)
That would be wrong I think

You have to multiply by

Then you take the 5.5 over

Divide it by -2

Making the points
(Original post by Pretish)

Divide the entire equation by -2 to get the coefficient of to be 1

so u got

then complete the square of whats inside the

so you got

then multiple the entire expression by 2 to remove the second brackets

from this you can see that the points are
When you find the minimum or maximum (vertex) of a quadratic, you don't set it equal to zero, as it isn't being solved. You complete the square, as was done correctly, giving

It may help to write this as

Now, the maximum value of is achieved when the smallest value of is subtracted from . As the bracket is squared, the smallest value to be subtracted is zero. Hence the maximum of is and it is achieved when .
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3 years ago
#6
(Original post by Integer123)
When you find the minimum or maximum (vertex) of a quadratic, you don't set it equal to zero, as it isn't being solved. You complete the square, as was done correctly, giving

It may help to write this as

Now, the maximum value of is achieved when the smallest value of is subtracted from . As the bracket is squared, the smallest value to be subtracted is zero. Hence the maximum of is and it is achieved when .
I didnt really know how to do it. I just went off the other guys working out which was wrong so thank you for teaching me something new. Even thought the guys method was wrong would he get the marks as the answer was correct.
1
3 years ago
#7
(Original post by Balkaran)
I didnt really know how to do it. I just went off the other guys working out which was wrong so thank you for teaching me something new. Even thought the guys method was wrong would he get the marks as the answer was correct.
the methods i used would still get u all the marks. I could not type out every single line of working properly from a computer near midnight.
1
3 years ago
#8
(Original post by Balkaran)
That would be wrong I think

You have to multiply by

Then you take the 5.5 over

Divide it by -2

Making the points
whats wrong? I got the right answer
0
3 years ago
#9
(Original post by Pretish)
whats wrong? I got the right answer
The equating to zero and your -5.5 (it's +5.5).
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3 years ago
#10
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3 years ago
#11
(Original post by RogerOxon)
The equating to zero and your -5.5 (it's +5.5).
(Original post by Pretish)
whats wrong? I got the right answer
(Original post by Balkaran)
I didnt really know how to do it. I just went off the other guys working out which was wrong so thank you for teaching me something new. Even thought the guys method was wrong would he get the marks as the answer was correct.
(Original post by Integer123)
When you find the minimum or maximum (vertex) of a quadratic, you don't set it equal to zero, as it isn't being solved. You complete the square, as was done correctly, giving

It may help to write this as

Now, the maximum value of is achieved when the smallest value of is subtracted from . As the bracket is squared, the smallest value to be subtracted is zero. Hence the maximum of is and it is achieved when .
(Original post by mathcool)

oh my life guys, the exact question was asked on a thread so i answered it there, and i just copied it. There are 2 ways to do this question, calculus and complting the square. In calculas u set the equation to 0, thats why i got confused and did the same here. Jeez people. XD
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3 years ago
#12
(Original post by Pretish)
There are 2 ways to do this question, calculus and complting the square. In calculas u set the equation to 0,
If you use calculus, you have to differentiate w.r.t. , and set that equal to 0. It's quite important to correct any mistakes quickly, so that the OP (and others) don't learn an incorrect method. It's not a reprimand, it's purely making sure that the way to solve a problem is full understood.
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3 years ago
#13
(Original post by RogerOxon)
If you use calculus, you have to differentiate w.r.t. , and set that equal to 0. It's quite important to correct any mistakes quickly, so that the OP (and others) don't learn an incorrect method. It's not a reprimand, it's purely making sure that the way to solve a problem is full understood.
ik. I did differentiate h and t lol.
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