Tolong bantu ngerjain

f(a-5)=5
(a-5)^2 + 2(a-5)- 3 = 5
(a^a-10a+25) +2a-10 -8 =0
a^2 -8a + 7 = 0
(a-7)(a-1) = 0
a=7 a=1