# find all numbers x

• Jan 24th 2010, 12:40 PM
alessandromangione
find all numbers x
if P=(-3,1) and Q=(x,4), find all numbers x such that the vector represented by PQ has lenght 5.

thank you
• Jan 24th 2010, 12:49 PM
Jhevon
Quote:

Originally Posted by alessandromangione
if P=(-3,1) and Q=(x,4), find all numbers x such that the vector represented by PQ has lenght 5.

thank you

what have you tried here?

what does PQ look like? how would you find it's size?
• Jan 24th 2010, 01:18 PM
alessandromangione
PQ must be like the resultant of a triangle formed by Q and P right?
I tried to find the vector of P and the 5 ( PQ) divided by the vector P...then this result divided by 4....
• Jan 24th 2010, 01:51 PM
Jhevon
Quote:

Originally Posted by alessandromangione
PQ must be like the resultant of a triangle formed by Q and P right?
I tried to find the vector of P and the 5 ( PQ) divided by the vector P...then this result divided by 4....

...huh? i think you are thinking about adding vectors P and Q. First, P and Q are not vectors here, thet are points. and you are not adding them

PQ = < x - (-3), 4 - 1 > = < x + 3, 3>

now finish up