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Mathematics 6 Online
OpenStudy (mathmath333):

Geometry question

OpenStudy (mathmath333):

If the point \(R(1,-2)\) divides externally the line segment joining \(P(2,5)\) and \(Q\) in the ratio \(3:4\) , what will be the co-ordinates of \(Q\)? \(\large \color{black}{\begin{align} &a.)\ (-3,6)\hspace{.33em}\\~\\ &b.)\ (2,-4)\hspace{.33em}\\~\\ &c.)\ (3,6)\hspace{.33em}\\~\\ &d.)\ (1,2)\hspace{.33em}\\~\\ \end{align}}\)

Parth (parthkohli):

You're directly applying the formula for external division.

OpenStudy (mathmath333):

u mean this one \(\large \color{black}{\begin{align}\ x=\dfrac{mx_2-nx_1}{m-n}\\\hspace{.33em}\\~\\ \end{align}}\)

Parth (parthkohli):

Precisely.

OpenStudy (mathmath333):

but i m not getting the answer from the choices

Parth (parthkohli):

Are you sure you chose your points and their values in the right order?

OpenStudy (rational):

none of the options even lie on the given line segment PR

OpenStudy (rational):

presuming you want a point Q such that R,P,Q are collinear

Parth (parthkohli):

True, I'm getting something else.

OpenStudy (rational):

easy way to convince and kill the question is by considering the slope RP slope of RP = 7 it is necessary that any two points on the same line must have same slope pick any of the options for Q and work the slope RQ none match, so another bogus question

OpenStudy (mathmath333):

ok the book is bogus

Parth (parthkohli):

Does your book give you the answer (3,6)? I'm kinda trying to see how they got to a wrong answer.

OpenStudy (mathmath333):

yes \((3,6)\) is given correct

OpenStudy (rational):

interesting, how did u get (3,6) PK

Parth (parthkohli):

They solved it like this:|dw:1432470971997:dw|

Parth (parthkohli):

\[1 = 3\cdot x - 4 \cdot 2 \Rightarrow x = 3\]\[-2 = 3\cdot y - 20 \Rightarrow y = 6\]It's evidently wrong.

Parth (parthkohli):

They made a really common mistake. External division does tend to confuse.

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