Not quite the 4 should be a 16, must have just forgot to multiply by the second 4. And 36-16=20

Also when you have 20k^2-16>0 draw this graph to find the ranges of k

Reply 28

monisj1

Original post by Underthecandle

Not quite the 4 should be a 16, must have just forgot to multiply by the second 4. And 36-16=20

Also when you have 20k^2-16>0 draw this graph to find the ranges of k

is K 4 / 2 square root 5?

Reply 29

Underthecandle

Original post by monisj1

is K 4 / 2 square root 5?

K can be a range of values.

Try scetching the graph of y=20k^2-16. The range of values k can be will be the parts of the graph where y>0

Reply 30

monisj1

Original post by Underthecandle

K can be a range of values.

Try scetching the graph of y=20k^2-16. The range of values k can be will be the parts of the graph where y>0

don't you work out K then sketch the graph?

Reply 31

Underthecandle

Original post by monisj1

don't you work out K then sketch the graph?

You work out where the graph crosses the axis first, is that what you mean?

Reply 32

monisj1

Original post by Underthecandle

You work out where the graph crosses the axis first, is that what you mean?

what is your final answer?

Reply 33

Underthecandle

Original post by monisj1

what is your final answer?

I have two ranges that k can be.

Where have you got up too? Have you got a range for k? Or have you got a graph?

Reply 34

monisj1

Original post by Underthecandle

I have two ranges that k can be.

Where have you got up too? Have you got a range for k? Or have you got a graph?

i got K>+2 root 5 and K< - 2 root 5

Reply 35

Underthecandle

Original post by monisj1

i got K>+2 root 5 and K< - 2 root 5

Is that 2/root5 or 2 x root 5?

Reply 36

monisj1

Original post by Underthecandle

Is that 2/root5 or 2 x root 5?

just 2 root 5

Reply 37

Underthecandle

Original post by monisj1

just 2 root 5

Try putting k=1 in 20k^2-16 and you'll get it is bigger than 0 but 1 isn't in your ranges. I think you've done the right working but just done a small error in the calculations at the end.

Reply 38

monisj1

[QUOTE="Underthecandle;50698037"]Try putting k=1 in 20k^2-16 and you'll get it is bigger than 0 but 1 isn't in your ranges. I think you've done the right working but just done a small error in the calculations at the end.[/QUOTE

i give up

Reply 39

Underthecandle

[QUOTE="monisj1;50698113"]

Original post by Underthecandle

Try putting k=1 in 20k^2-16 and you'll get it is bigger than 0 but 1 isn't in your ranges. I think you've done the right working but just done a small error in the calculations at the end.[/QUOTE

i give up

But your sooo close. When you solve 20k^2-16=0 what did you get?