a) x² - 8x + 7 = x² -x - 7x + 7
= x (x-1) - 7 (x-1)
= (x-1)(x-7)
b) x^4 - 2x³ +x² = x^4 - x³ - x³ + x²
= x³ (x-1) - x² (x-1)
= (x-1)(x³ - x²)
= (x-1) x² ( x-1)
= [x(x-1)]²
c) m^6 - 2m^4 - m + m² + m³ = m³ - m + m^6 - m^4 - m^4 +m²
= (m^3 - m) + (m^6 - m^4) - (m^4 - m^2)
= [m(m² - 1) + [ m^4 ( m² - 1)] - [m² (m² -1)]
= (m²-1) (m+m^4 - m²)
= (m-1)(m+1). m (m³-m+1)
= m (m-1) ( m+1) ( m³ - m +1)
ỦNG HỘ MIK NHA!!!!!!!!!!!!!!!!!!!!!!!!!!!! CHÚC BN HỌC TỐT :)))))))))))))))
