tentukan nilai a jika : a). x^3+2x^2-ax+1 dibagi oleh (x-1) bersisa 5 b). 2x^3+x^2-3x+a dibagi oleh (x-2) - 11 . mohon bantuannya

Dalil Sisa
Nilai fungsi = sisa
f(x) = s(x)

a)
f(x) = x³ + 2x² - ax + 1
p(x) = x -1 --> x -1 =0 --> x = 1
s(1) = 5
f(1) = s(1)

1³ + 2(1)² - a(1) + 1= 5
1 + 2 - a + 1 = 5
4 - a = 5
a = 4 - 5
a =  -1

2)
f(x) = 2x³ + x² -3x + a
p(x)= x-2 --> x-2 =0 --> x= 2
s(2) = -11

f(2) = s(2)
2(2)³ + (2)² - 3(2) + a = -11
2(8) + 4 - 6 + a = -11
16 + 4 - 6 + a = - 11
14 + a = - 11
a = -11 - 14
a = -25