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The straight line graph y=2x+k intersects the x-axis at pointA and y-axis at point...

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phanpal999 | Student, Grade 8 | (Level 1) Salutatorian

Posted May 5, 2013 at 6:47 AM via web

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The straight line graph y=2x+k intersects the x-axis at pointA and y-axis at point B.Given that the length of AB is `sqrt(5)` units,find the values of k

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pramodpandey | College Teacher | (Level 3) Valedictorian

Posted May 5, 2013 at 7:15 AM (Answer #1)

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The line y=2x+k , meet  x axis  at  A, Thus coordinate of A is (-k/2,0).

meet  y axis  at B, Thus coordinate of B is (0,k).

distance beetween A and B =sqrt(5)

But  by distance formula

`AB=sqrt((x_1-x_2)^2+(y_1-y_2)^2)`

`sqrt(5)=sqrt((-k/2)^2+k^2)`

squaring both side ,we have

`5=k^2/4+k^2`

`5=k^2(1/4+1)`

`k^2=4`

`Thus`

`k=+-2`

Thus line is

`y=2x+-2`

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