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a^2 + b^2 - 2a + 2b - 2ab
= (a^2 - 2ab + b^2) - 2(a - b)
= (a - b)^2 - 2(a - b)
= (a - b)(a - b - 2)
a^2+b^2-2a+2b-2ab
=(a^2+b^2-2ab)-(2a-2b)
=(a-b)^2-2(a-b)
=(a-b)(a-b-2)
\(P = 2a^3 + 7a^2b + 7ab^2 + 2b^3\)
\(=2a^3+2a^2b+5a^2b+5ab^2+2ab^2+2b^3\)
\(=2a^2(a+b)+5ab(a+b)+2b^2(a+b) \)
\(=(2a^2+5ab+2b^2)(a+b)\)
\(=(2a^2+4ab+ab+2b^2)(a+b)\)
\(=[2a(a+2b)+b(a+2b)](a+b)\)
\(=(2a+b)(2b+a)(a+b)\)
P=2a3+7a2b+7ab2+2b3
=2a3+2a2b+5a2b+5ab2+2ab2+2b2
=(2a3+2a2b)+(5a2b+5ab2)+(2ab2+2b3)
=2a2(a+b)+5ab(a+b)+2b2(a+b)
=(a+b)(2a2+5ab+2b2)
=(a+b)[2a2+4ab+ab+2b2]
=(a+b)[2a(a+2b)+b(a+2b)]
=(a+b)(2a+b)(a+2b)
TL
a) x2 - 5x - 4x + 20 = x ( x - 5 ) - 4 ( x - 5) = ( x -4 ) ( x -5)
b) Cái này không phân tích được bạn nhé
Khi nào rảnh vào kênh H-EDITOR xem vid nha!!! Thanks!
a(a+2b)3 -b(2a+b)3
\(=a\left(a^3+6a^2b+12ab^2+8b^3\right)-b\left(8a^3+12a^2b+6ab^2+b^3\right)\)
\(=a^4+6a^3b+12a^2b^2+8ab^3-8a^3b-12a^2b^2-6ab^3-b^4\)
\(=a^4-2a^3b+2ab^3-b^4\)
\(=\left[\left(a^2\right)^2+ \left(b^2\right)^2\right]-2ab\left(a^2-b^2\right)\)
\(=\left(a^2+b^2\right)\left(a^2-b^2\right)-2ab\left(a^2-b^2\right)\)
\(=\left(a^2-b^2\right)\left(a^2-2ab+b^2\right)\)
\(=\left(a-b\right)\left(a+b\right)\left(a-b\right)^2\)
\(=\left(a-b\right)^3\left(a+b\right)\)
\(a.\left(a+2b\right)^3-b.\left(2a+b\right)^3\)
\(=a.\left(a+20+b\right)^3-b.\left(20+a+b\right)^3\)
\(=\left(a-b\right).\left(a+20+b\right)^3\)
Thế này có phải là phân tích đa thức thành nhân tử k ạ
Chúc bạn học tốt
\(a\left(a+2b\right)^3-b\left(2a+b\right)^3\)
\(=\left(a^4+6a^3b+12a^2b^2+8ab^3\right)-\left(b^4+8a^3b+12a^2b^2+6ab^3\right)\)
\(=a^4-b^4-2a^3b+2ab^3\)
\(=\left(a^2-b^2\right)\left(a^2+b^2\right)-2ab\left(a^2-b^2\right)\)
\(=\left(a^2-b^2\right)\left(a^2-2ab+b^2\right)\)
\(=\left(a-b\right)^3\left(a+b\right)\)
OK ?
2a2b2+2a2c2+2b2c2-a4-b4-c4
=4a2b2-(a4+2a2b2+b4)+(2b2c2+2a2c2)-c4
=2(ab)2-(a+b)2+2c2(a2+b2)+c4
=2(ab)2-[(a+b)2-2c2(a2+b2)+c4]
=2(ab)2-(b2+a2-c2)2
=[(a+b)2-c2][-(a-b)2+c2]
=(a+b-c)(a+b+c)(c-a+b)(a+c-b)
\(2a^2b^2+2a^2c^2+2b^2c^2-a^4-b^4-c^4\)
\(=4a^2b^2-\left(a^4+2a^2b^2+b^4\right)+\left(2b^2c^2+2a^2c^2\right)-c^4\)
\(=2\left(ab\right)^2-\left(a+b\right)^2+2c^2\left(a^2+b^2\right)+c^4\)
\(=2\left(ab\right)^2-\left[\left(a+b\right)^2-2c^2\left(a^2+b^2\right)+c^4\right]\\ =2\left(ab\right)^2-\left(b^2+a^2-c^2\right)^2\)
=\(\left[\left(a+b\right)^2-c^2\right]\left[-\left(a-b\right)^2+c^2\right]\\ =\left(a+b+c\right)\left(a+b+c\right)\left(c-a+b\right)\left(a+c-b\right)\)
\(\left(a+b\right)^2-\left(a-2b\right)^2\)
\(=\left[\left(a+b\right)+\left(a-2b\right)\right]\left[\left(a+b\right)-\left(a-2b\right)\right]\)
\(=\left(a+b+a-2b\right)\left(a+b-a+2b\right)\)
\(=\left(2a-b\right).3b\)
\(=3b.\left(2a-b\right)\)