Bài làm
a) 2a²x³ - ax³ - a⁴ - x³a² - ax³ - 2x⁴
= 2a²x³ - ax³ - a⁴ - a²x³ - ax³ - 2x⁴
= ( 2a²x³ - a²x³ ) - ( ax³ + ax³ ) - a⁴ - 2ax⁴
= a²x³ - 2ax³ - a⁴ - 2ax⁴
b) 3xx⁴ + 4xx³ - 5x²x³ - 5x²x²
= 3x⁵ + 4x⁴ - 5x⁵ - 5x⁴
= ( 3x⁵ - 5x⁵ ) + ( 4x⁴ - 5x⁴ )
= -2x⁵ - x⁴
c) 3a - 4b² - 0,8b . 4b² - 2ab . 3b + b . 3b² - 1
= 3a - 4b² - 3,2b³ - 6ab² + 3b³ - 1
= 3a - 4b² - 0,2b³ - 6ab² - 1
d) 5x.2y² - 5x.3xy - x²y + 6xy²
= 10xy² - 15x²y - x²y + 6xy²
= ( 10xy² + 6xy² ) - ( 15x²y + x²y )
= 16xy² - 16x²y
a)\(2a^2\)\(x^3\)-\(ax^3\)-\(a^4\)-\(x^3a^2\)-\(ax^3\)-\(2x^4\)
=(\(2a^2x^3-x^3a^2)\)+\((-ax^3-ax^3)\)-\(ax^4-2x^4\)
=\(a^2x^3-2ax^3-ax^4-2x^4\)
b)\(3xx^4+4xx^3-5x^2x^3-5x^2x^2
\)
=\(3x^5+4x^4-5x^5-5x^4\)
=\((3x^5-5x^5)+(4x^4-5x^4)\)
=\(-2x^5-x^4\)
d)\(5x.2y^2-5x.3xy-x^2y+6xy^2\)
=\((5.2)xy^2+(-5.3)xxy-x^2y+6xy^2\)
=\(10xy^2-15x^2y-x^2y+6xy^2\)
=\((10xy^2+6xy^2)+(-15x^2y-x^2y)\)
=\(16xy^2-16x^2y\)
câu c) mik ko biết làm
