B1 a,làm phép chia:( x^2 + 2x+ 1 ):(x+1)
b, Rút gọn biểu thức (x+y)^2 – (x-y)^2-4(x-1)y
B2phân tích đa thức thành nhân tử
a,x^2 +3x+3y+xy
b,x^3+5x^2+6x
B3: Cho bt Q=x+3/2x+1 – x-7/2x+1
a, Thu gọn bt Q
b, Tìm giá trị nguyên của x để Q nhận giá trị nguyên
Đáp án:
b1
a,
b,
=????^2+????????+????(????+????)−1(????−????)^2−4(????−1)⋅????
=????^2+2????????+????^2−1(????−????)^2−4(????−1)⋅????
=????^2+2????????+????^2−1(????−????)(????−????)−4(????−1)⋅????
=????^2+2????????+????^2−1(????^2−????????−????(????−????))−4(????−1)⋅????
=????^2+2????????+????^2−1(????^2−????????−????????+????^2)−4(????−1)⋅????
=????^2+2????????+????^2−1(????^2−2????????+????^2)−4(????−1)⋅????
=????^2+2????????+????^2−1????^2+2????????−1????^2−4????????+4????
=2????????+????^2+2????????−1????^2−4????????+4????
=????^2−1????^2+4????
=4y
b2
a,=x^2+xy+3(x+y)
=x(x+y)+3(x+y)
=(x+3)(x+y)
b,x^3+5x^2+6x
=x(x^2+3x+2x+6)
=x(x+2)(x+3)
b3
a, (x+3)/(2x+1)-(x-7)(2x+1)
=(x+3-x+7)/(2x+1)
=10/(2x+1)
b,