[xXxiKillxXx]

I know you have to do more work to find the actual value of a, but it says a(2t-1)=0, so isn't a=0 a solution?

[raheem94]

(Original post by xXxiKillxXx)


I know you have to do more work to find the actual value of a, but it says a(2t-1)=0, so isn't a=0 a solution?

You are confusing constants with variables.

If you have then

But if you have then and not

is a constant.

[LeeM1]

It doesn't satisfy the x and y equations, only the y.

[xXxiKillxXx]

(Original post by raheem94)
You are confusing constants with variables.

If you have then

But if you have then and not

is a constant.

Something can only be a constant if it has one value right? So Isn't x a constant also?

[raheem94]

(Original post by xXxiKillxXx)
Something can only be a constant if it has one value right? So Isn't x a constant also?

Yes, constant has only one value.

is a variable, it can take many values.

In the question it is specified that is a constant.

[xXxiKillxXx]

(Original post by raheem94)
Yes, constant has only one value.

is a variable, it can take many values.

In the question it is specified that is a constant.

Ah thanks

[xXxiKillxXx]

(Original post by raheem94)
Yes, constant has only one value.

is a variable, it can take many values.

In the question it is specified that is a constant.

Wait, if a is a constant and it can only take one value, how do we know (initially) that value isn't 0 as opposed to 2x-1 = a ?

[raheem94]

(Original post by xXxiKillxXx)
Wait, if a is a constant and it can only take one value, how do we know (initially) that value isn't 0 as opposed to 2x-1 = a ?

If a=0 then , then will be zero for all values of , so how can the curve pass through the point

[xXxiKillxXx]

(Original post by raheem94)
If a=0 then , then will be zero for all values of , so how can the curve pass through the point

That makes sense, thanks!

[Z.93]

x=4=4at² --> rearranged to at²=1
y=0=a(2t+1) --> rearranged to t=-0.5 (2at+a=0>>2at=-a>>2t=-1>>t=-0.5)

put t=-0.5 into at²=1 then you get a= 1/t² (1/0.25)

therefore a=4