phân tích đa thức thành nhân tử,
1)A(B^2+C^2+CB)+B(A^2+C^2+AC)+C(A^2+B^2+AB)
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a ( b2 + c2 + bc ) + b ( a2 + c2 + ac ) + c ( a2 + b2 + ab )
= ab2 + ac2 + abc + ba2 + bc2 + abc + ca2 + cb2 +abc
= ( ab2 + a2b + abc ) + ( ac2 + a2c + abc ) + ( bc2 + b2c + abc )
= ab ( a + b + c ) + ac ( a + b + c ) + bc ( a + b + c )
= ( a + b + c ) ( ab + ac + bc )
\(a\left(b^2+c^2+bc\right)+b\left(a^2+c^2+ac\right)+c\left(a^2+b^2+ab\right)\)
\(=ab^2+ac^2+abc+ba^2+bc^2+abc+ca^2+cb^2+abc\)
\(=\left(ab^2+ba^2+abc\right)+\left(bc^2+cb^2+abc\right)+\left(ca^2+ac^2+abc\right)\)
\(=ab\times\left(a+b+c\right)+bc\times\left(a+b+c\right)+ca\times\left(a+b+c\right)\)
\(=\left(a+b+c\right)\times\left(ab+bc+ca\right)\)
ai có thể giảng cho mình dạng toán tìm số tự nhiên thỏa mãn đièu kiện chia hết ko
hãy nêu ra cách giải cụ thể cho câu sau 3a-11 chia hết cho a+2 tìm a
\(\left(a+b+c\right)\left(ab+bc+ca\right)-abc\)
\(=\left(a+b+c\right)\left(ab+bc\right)+\left(a+b+c\right)ac-abc\)
\(=\left(ab+b^2+bc\right)\left(a+c\right)+\left(a+c\right)ac+abc-abc\)
\(=\left(a+c\right)\left(ab+b^2+bc+ac\right)\)
\(=\left(a+b\right)\left(b+c\right)\left(c+a\right)\)
\(=a^2b-ab^2+b^2c-bc^2+ac^2-a^2c\)
\(=a^2\left(b-c\right)+bc\left(b-c\right)-a\left(b-c\right)\left(b+c\right)\)
\(=\left(b-c\right)\left(a^2-bc-ab-ac\right)\)
\(=\left(b-c\right)\left[a\left(a-b\right)-c\left(a-b\right)\right]\)
\(ab\left(a-b\right)+bc\left(b-c\right)+ca\left(c-a\right)\)
\(=ab\left(a-b\right)+bc\left(b-c\right)-ca\left(a-c\right)\)
\(=ab\left(a-b\right)+bc\left(b-c\right)-ca\left(a-b+b-c\right)\)
\(=ab\left(a-b\right)+bc\left(b-c\right)-ca\left(a-b\right)-ca\left(b-c\right)\)
\(=\left(a-b\right)\left(ab-ca\right)+\left(b-c\right)\left(bc-ca\right)\)
\(=\left(a-b\right)a\left(b-c\right)+\left(b-c\right)c\left(b-a\right)\)
\(=\left(a-b\right)a\left(b-c\right)-\left(b-c\right)c\left(a-b\right)\)
\(=\left(a-b\right)\left(b-c\right)\left(a-c\right)\)
mình làm vội, có chỗ nào sai bạn thông cảm nha
Ta có:
\(A=8abc+4\left(ab+bc+ca\right)+2\left(a+b+c\right)+1\)
\(A=\left(8abc+4ab\right)+\left(4bc+2b\right)+\left(4ca+2a\right)+\left(2c+1\right)\)
\(A=4ab\left(2c+1\right)+2b\left(2c+1\right)+2a\left(2c+1\right)+\left(2c+1\right)\)
\(A=\left(2c+1\right)\left(4ab+2a+2b+1\right)\)
\(A=\left(2c+1\right)\left[2a\left(2b+1\right)+\left(2b+1\right)\right]\)
\(A=\left(2a+1\right)\left(2b+1\right)\left(2c+1\right)\)
Ta có:\(A=8abc+4\left(ab+bc+ca\right)+2\left(a+b+c\right)+1\)
\(=8abc+4ab+4bc+4ca+2a+2b+2c+1\)
\(=\left(8abc+4ab\right)+\left(4bc+2b\right)+\left(4ca+2a\right)+\left(2c+1\right)\)
\(=4ab\left(2c+1\right)+2b\left(2c+1\right)+2a\left(2c+1\right)+\left(2c+1\right)\)
\(=\left(2c+1\right)\left(4ab+2b+2a+1\right)\)
\(=\left(2c+1\right)\left[2b\left(2a+1\right)+\left(2a+1\right)\right]\)
\(=\left(2c+1\right)\left(2b+1\right)\left(2a+1\right)\)
\(\left(a+b+c\right)\left(ab+bc+ca\right)-abc\)
\(=\left(a+b+c\right)\left(ab+bc\right)+\left(a+b+c\right)ac-abc\)
\(=\left(ab+b^2+bc\right)\left(a+c\right)+\left(a+c\right)ac+abc-abc\)
\(=\left(a+c\right)\left(ab+b^2+bc+ac\right)\)
\(=\left(a+b\right)\left(b+c\right)\left(c+a\right)\)