Tolong kerjakan no 20, terima kasih

Matriks singular
Det = 0
(p - 1)q = p(1 - q)
2pq = p + q

2x² + x - a = 0
Akar2nya : p dan q
p + q = -b/a = -1/2
pq = c/a = -a/2

2pq = p + q
2 . -a/2 = -1/2
-a = -1/2
a = 1/2