c) (8x^3 – x^2 + 1)(x^2 – 1);
Giải thích
c) (8x3 – x2 + 1)(x2 – 1)
= 8x3 . (x2 – 1) – x2 . (x2 – 1) + (x2 – 1)
= 8x5 – 8x3 – x4 + x2 + x2 – 1
= 8x5 – x4 – 8x3 + 2x2 – 1.
c) (8x3 – x2 + 1)(x2 – 1)
= 8x3 . (x2 – 1) – x2 . (x2 – 1) + (x2 – 1)
= 8x5 – 8x3 – x4 + x2 + x2 – 1
= 8x5 – x4 – 8x3 + 2x2 – 1.