Jawabanmu

2014-08-15T22:08:50+07:00
F(x) = x⁴+ax³-5x²-x+4 = ...
f(-1) = 
 (-1)^{4} +a(-1)^{3}-5(-1)^{2}-(-1)+4=-7
f(-1) = 1-a-5+1+4=-7
f(-1) = 1-a=-7
f(-1) = -a=-7-1
f(-1) = -a=-8 (jika pada hasil akhir variable masih bernilai negatif (-) maka harus dihilangkan
f(-1) = a=8