Question

Find y if distance between A(2,y) and B(5,7) is 5 units

Answer 1

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distance=[(x2-x1)^2+(y2-y1)]^1/2

here x1=2 x2=-1 y1=-2 y2=y distance=5

5=[(-1-1)^2+(y+2)^2]^1/2

5=[4+y^2+4+4y]^1/2

squaring on both side

25=4+y^2+4+4y

y^2+4y+8-25=0

y^2+4y-17=0

Answer 2

distance=[(x2-x1)^2+(y2-y1)]^1/2

here x1=2 x2=-1 y1=-2 y2=y distance=5

5=[(-1-1)^2+(y+2)^2]^1/2

5=[4+y^2+4+4y]^1/2

squaring on both side

25=4+y^2+4+4y

y^2+4y+8-25=0

y^2+4y-17=0