Answer:
XY ≡≡ XZ
9a² - 30 = 3a
3a² - 10 - a = 0
3a² - a - 10 = 0
a = 1 ± √[1 –4(3)(-10))]/2(3)
a = ⅙ ± √[ 1 + 120]/6
a = ⅙ ± √[121]/6
a = ( 1 ± 11)/6.... taking the positive.
a = 12/6
a = 2 (^^)
