Cho P(x) là một đa thức bậc bốn thỏa mãn các điều kiện P(x) chia x^2+1 dư 2x-1 và chia cho x^2+2 dư 3x-1 và P(1)=157. Tính P(-4) Cho P(x) là một đa thức bậc bốn thỏa mãn các điều kiện P(x) chia x^2+1 dư 2x-1 và chia cho x^2+2 dư 3x-1 và P(1)=157. Tính P(-4)
Tham khảo câu trả lời từ Trợ lý ảo Lazi Để tính P(-4), ta cần tìm đa thức P(x) trước. Theo đề bài, P(x) chia x^2+1 dư 2x-1 và chia cho x^2+2 dư 3x-1. Điều này có nghĩa là tồn tại hai đa thức Q(x) và R(x) sao cho: P(x) = Q(x)(x^2+1) + (2x-1) (1) P(x) = R(x)(x^2+2) + (3x-1) (2) Ta cần tìm Q(x) và R(x). Để làm điều này, ta sẽ thực hiện phép chia đa thức. (1) chia cho x^2+1: P(x) = Q(x)(x^2+1) + (2x-1) => P(i) = Q(i)(i^2+1) + (2i-1) (với i là căn bậc hai của -1) => P(i) = Q(i)(-1+1) + (2i-1) => P(i) = 2i-1 (2) chia cho x^2+2: P(x) = R(x)(x^2+2) + (3x-1) => P(√2) = R(√2)(√2^2+2) + (3√2-1) => P(√2) = R(√2)(2+2) + (3√2-1) => P(√2) = 4R(√2) + (3√2-1) Vì P(i) = 2i-1, ta có thể thay i = √2 vào để tìm giá trị của P(√2): P(√2) = 4R(√2) + (3√2-1) => 2√2 - 1 = 4R(√2) + (3√2-1) => 2√2 = 4R(√2) + 3√2 => 2√2 - 3√2 = 4R(√2) => -√2 = 4R(√2) => R(√2) = -√2/4 Vậy, ta đã tìm được R(x) = -x/4. Tiếp theo, ta sẽ tìm Q(x) bằng cách thay R(x) vào (1): P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) => P(x) = Q(x)(x^2+1) + (2x-1) =>