Question

find y if the distance between D(y,7) and E(1,15)is 10​

Answer 1

10=√(1-y)²+(15-7)²

10=√1+y²-2y+64

100=y²-2y+65

y²-2y-35

y²-7y+5y-35

y(y-7)+5(y-7)

(y-7)(y+5)

y=7or y=-5