Phân tích đa thức thành nhân tử bằng cách tách hạng tử:
\(16x-5x^2-2\) \(7x-6x^2-2\)
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a) \(x^3+4x^2-21x\)
\(=x\left(x^2+4x-21\right)\)
\(=x\left(x^2-3x+7x-21\right)\)
\(=x\left[x\left(x-3\right)+7\left(x-3\right)\right]\)
\(=x\left(x-3\right)\left(x+7\right)\)
b) \(5x^3+6x^2+x\)
\(=x\left(5x^2+6x+1\right)\)
\(=x\left(5x^2+5x+x+1\right)\)
\(=x\left[5x\left(x+1\right)+\left(x+1\right)\right]\)
\(=x\left(x+1\right)\left(5x+1\right)\)
c) \(x^3-7x+6\)
\(=x^3+2x^2-3x-2x^2-4x+6\)
\(=x\left(x^2+2x-3\right)-2\left(x^2+2x-3\right)\)
\(=\left(x-2\right)\left(x^2+2x-3\right)\)
\(=\left(x-2\right)\left(x-1\right)\left(x+3\right)\)
d) \(3x^3+2x-5\)
\(=3x^3+3x^2+5x-3x^2-3x-5\)
\(=x\left(3x^2+3x+5\right)-\left(3x^2+3x+5\right)\)
\(=\left(x-1\right)\left(3x^2+3x+5\right)\)
f)\(x^2-5x-14=x^2-7x+2x-14=x\left(x-7\right)+2\left(x-7\right)=\left(x-7\right)\left(x+2\right)\)
i)\(x^2-7x+10=x^2-2x-5x+10=x\left(x-2\right)-5\left(x-2\right)=\left(x-5\right)\left(x-2\right)\)
h)\(x^2-7x+12=x^2-3x-4x+12=x\left(x-3\right)-4\left(x-3\right)=\left(x-4\right)\left(x-3\right)\)
g)\(x^2+6x+5=x^2+x+5x+5=x\left(x+1\right)+5\left(x+1\right)=\left(x+1\right)\left(x+5\right)\)
f)\(x^2-5x-14=x^2-7x+2x-14\)
\(=\left(x+2\right)\left(x-7\right)\)
i)\(x^2-7x+10=x^2-5x-2x+10\)
\(=\left(x-2\right)\left(x-5\right)\)
h)\(x^2-7x+12=x^2-4x-3x+12\)
\(=\left(x-3\right)\left(x-4\right)\)
g)\(x^2+6x+5=x^2+x+5x+5\)
\(=\left(x+5\right)\left(x+1\right)\)
1/ \(2x^2+3x-5=\left(2x^2+2x\right)-\left(5x+5\right)=2x\left(x+1\right)-5\left(x+1\right)=\left(x+1\right)\left(2x-5\right)\)
2/ \(16x-5x^2-3=\left(15x-5x^2\right)+\left(x-3\right)=5x\left(3-x\right)-\left(3-x\right)=\left(3-x\right)\left(5x-1\right)\)
3/ \(7x-6x^2-2=\left(3x-6x^2\right)-\left(2-4x\right)=3x\left(1-2x\right)-2\left(1-2x\right)=\left(1-2x\right)\left(3x-2\right)\)
4/ \(x^2+5x-6=\left(x^2-x\right)+\left(6x-6\right)=x\left(x-1\right)+6\left(x-1\right)=\left(x-1\right)\left(x+6\right)\)
\(12x^2+7x-12=12x^2-5x+12x-12\)
\(=x\left(12x-5\right)+12\left(x-1\right)\)
Đề sai rồi bạn ời
1) 6x^2 + 7x - 5
=6x2-3x+10x-5
=3x.(2x-1)+5.(2x-1)
=(2x-1)(3x+5)
2) 10x^2 - 13x - 3
=10x2+2x-15x-3
=2x(5x+1)-3(5x+1)
=(5x+1)(2x-3)
\(6x^2+7x-5\)
\(=6x^2-3x+10x-5\)
\(=3x\left(2x-1\right)+5\left(2x-1\right)\)
\(=\left(2x-1\right)\left(3x+5\right)\)
a, = (x^3-x^2)-(4x^2-4x)+(4x-4)
= (x-1).(x^2-4x+4) = (x-1).(x-2)^2
b, = (x^3+x^2)-(10x^2+10x)+(16x+16)
= (x+1).(x^2-10x+16)
= (x+1).[ (x^2-2x)-(8x-16) ] = (x+1).(x-2).(x-8)
k mk nha
a)= (x^3-x^2)-(4x^2-4x)+(4x-4)
= (x-1).(x^2-4x+4)
= (x-1).(x-2)^2
b)= (x^3+x^2)-(10x^2+10x)+(16x+16)
= (x+1).(x^2-10x+16)
= (x+1).[ (x^2-2x)-(8x-16) ]
= (x+1).(x-2).(x-8)
P/s tham khảo nha
a,x2 - 13x + 36
= x2 - 4x - 9x + 36
= x(x - 4) - 9(x - 4)
= (x - 4)(x - 9)
b,x2 + 3x - 18
= x2 - 9 + 3x - 9
= (x - 3)(x + 3) + 3(x - 3)
= (x - 3)(x + 3 + 3)
= (x - 3)(x + 6)
c,x2 - 5x - 24
= x2 + 3x - 8x - 24
= x(x + 3) - 8(x + 3)
= (x + 3)(x - 8)
d,3x2 - 16x + 5
= 3x2 - 15x - x + 5
= 3x(x - 5) - (x - 5)
= (x - 5)(3x - 1)
e, 8x2 + 30x + 7
= 8x2 + 2x + 28x + 7
= 2x(4x + 1) + 7(4x + 1)
= (4x + 1)(2x + 7)
g,2x2 - 5x - 12
= 2x2 - 8x + 3x - 12
= 2x(x - 4) + 3(x - 4)
= (x - 4)(2x + 3)
i,x4 + 4
= x4 + 4x2 + 4 - 4x2
= (x2 + 2)2 - (2x)2
= (x2 + 2 - 2x)(x2 + 2 + 2x)
Phân tích đa thức thành nhân tử bằng cách tách một số hạng tử thành nhiều số hạng khác
a) x^2+4x+3
b) 4x^2-4x-3
c)x^2-x-12
d) 4x^4-4x^2-8y^4
SAI ĐỀ CÂU A NHÉ
CÂU B Ở CÂU HỎI TƯƠNG TỰ