Question

find the value of x if the distance between a(9,-5) and b(12,x)is three.

Answer 1

AB=√(12-9)(12-9)-(x+5)(x+5)
3=√9+x.x+10x+25
on Squaring both sides,
9=9+x.x+10x+25
on solving, X= -5

Answer 2

By distance formula,

d=distance.

d=√{(12-9)²+(x-(-5))²}

3=√{3²+(x+5)²}

3²=3²+(x+5)²

0=x²+25+10x

0=x²+10x+25

0=x²+(5+5)x+25

0=x²+5x+5x+25

0=x(x+5)+5(x+5)

0=(x+5)(x+5)

Then x=-5

I hope this much will help you