# complex numbers what does this mean

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a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p

Is the questions implying that P is 5,7?? shouldn't they be more explicit?

sketch the locus of p

Is the questions implying that P is 5,7?? shouldn't they be more explicit?

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(Original post by

a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p

Is the questions implying that P is 5,7?? shouldn't they be more explicit?

**vix.xvi**)a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p

Is the questions implying that P is 5,7?? shouldn't they be more explicit?

No. p/P is the locus of all points satisfying the constraint.

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#3

I think the question is expecting P to be a point satisfying the equation |z - 5 + 7i| = 5, and you're supposed to sketch the set of all possible P. (Although what you've written doesn't actually say P has anything to do with z, in which case you don't really know *anything* about P!).

Note also that with |z - 5 + 7i|, the "point of interest" is 5-7i (because you should think of |z - 5 + 7i| as |z - (5-7i)|). I can't think of any interpretation of any of this where P = (5, 7) would make sense.

Note also that with |z - 5 + 7i|, the "point of interest" is 5-7i (because you should think of |z - 5 + 7i| as |z - (5-7i)|). I can't think of any interpretation of any of this where P = (5, 7) would make sense.

Last edited by DFranklin; 1 month ago

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(Original post by

Unless there is more to the question....

No. p/P is the locus of all points satisfying the constraint.

**mqb2766**)Unless there is more to the question....

No. p/P is the locus of all points satisfying the constraint.

(Original post by

I think the question is expecting P to be a point satisfying the equation |z - 5 + 7i| = 5, and you're supposed to sketch the set of all possible P. (Although what you've written doesn't actually say P has anything to do with z, in which case you don't really know *anything* about P!).

Note also that with |z - 5 + 7i|, the "point of interest" is 5-7i (because you should think of |z - 5 + 7i| as |z - (5-7i)|). I can't think of any interpretation of any of this where P = (5, 7) would make sense.

**DFranklin**)I think the question is expecting P to be a point satisfying the equation |z - 5 + 7i| = 5, and you're supposed to sketch the set of all possible P. (Although what you've written doesn't actually say P has anything to do with z, in which case you don't really know *anything* about P!).

Note also that with |z - 5 + 7i|, the "point of interest" is 5-7i (because you should think of |z - 5 + 7i| as |z - (5-7i)|). I can't think of any interpretation of any of this where P = (5, 7) would make sense.

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#5

(Original post by

there is a part b and c but its not related/doesn't hv any useful info

ahh kk thanks so the info about P is redundant then?

**vix.xvi**)there is a part b and c but its not related/doesn't hv any useful info

ahh kk thanks so the info about P is redundant then?

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(Original post by

Pretty much. They often talk about a point locus though.

**mqb2766**)Pretty much. They often talk about a point locus though.

sorry to disturb you again, but im just looking at some more questions which have similar wording and i keep getting confused about what they mean? In the example i gave ( a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p), is it trying to say that z is = p? and the only reason they've specified is so that its a 'point' and not a vector type thing?

Last edited by Qxi.xli; 1 month ago

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#7

(Original post by

ahh ok thanks

sorry to disturb you again, but im just looking at some more questions which have similar wording and i keep getting confused about what they mean? In the example i gave ( a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p), is it trying to say that z is = p? and the only reason they've specified is so that its a 'point' and not a vector type thing?

**vix.xvi**)ahh ok thanks

sorry to disturb you again, but im just looking at some more questions which have similar wording and i keep getting confused about what they mean? In the example i gave ( a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p), is it trying to say that z is = p? and the only reason they've specified is so that its a 'point' and not a vector type thing?

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#8

you need to sketch the locus of all values of z where |z-5+7i| = 5

Think what |z| = 5 would look like

then think of how you need to translate it to make it |z-5+7i|=5

P appears to me to be irrelevent for this bit

Think what |z| = 5 would look like

then think of how you need to translate it to make it |z-5+7i|=5

P appears to me to be irrelevent for this bit

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#9

**vix.xvi**)

ahh ok thanks

sorry to disturb you again, but im just looking at some more questions which have similar wording and i keep getting confused about what they mean? In the example i gave ( a complex no. is represented by the point P on the argand diagram. Given that I z- 5 +7iI =5,

sketch the locus of p), is it trying to say that z is = p? and the only reason they've specified is so that its a 'point' and not a vector type thing?

Last edited by mqb2766; 1 month ago

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(Original post by

Have you tried using these PPTs https://www.drfrostmaths.com/sow.php...term=CorePure1

**Muttley79**)Have you tried using these PPTs https://www.drfrostmaths.com/sow.php...term=CorePure1

(Original post by

In effect, yes. z is an arbitrary complex variable and they want you to think about the (z=)P points on the locus which satisfy the magnitude and/or phase constraint(s).

**mqb2766**)In effect, yes. z is an arbitrary complex variable and they want you to think about the (z=)P points on the locus which satisfy the magnitude and/or phase constraint(s).

(Original post by

you need to sketch the locus of all values of z where |z-5+7i| = 5

Think what |z| = 5 would look like

then think of how you need to translate it to make it |z-5+7i|=5

P appears to me to be irrelevent for this bit

**Fibonacci28**)you need to sketch the locus of all values of z where |z-5+7i| = 5

Think what |z| = 5 would look like

then think of how you need to translate it to make it |z-5+7i|=5

P appears to me to be irrelevent for this bit

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