Question

1) Tim chu so a, b sao a56b chia het cho 45.

2) Phan tich da thuc sau thanh nhan tu: x³ + 4x² - 29x + 24

Answer 1

2) ta có \(x^3+4x^2-29x+24=x^3+8x^2-4x^2-32x+3x+24\)

              \(=x^2\left(x+8\right)-4x\left(x+8\right)+3\left(x+8\right)=\left(x+8\right)\left(x^2-4x+3\right)\)

               \(=\left(x+8\right)\left(x^2-x-3x+3\right)=\left(x-8\right)\left[x\left(x-1\right)-3\left(x-1\right)\right]=\left(x+8\right)\left(x-1\right)\left(x-3\right)\)