Question

Thu gọn đa thức sau :

a) A= 5xy - 3,5y² - 2xy +1,3xy +3x - 2y

b) B= \(\dfrac{1}{2}\)ab² - \(\dfrac{7}{8}\)ab² + \(\dfrac{3}{4}\)a²b - \(\dfrac{3}{8}\)a²b - \(\dfrac{1}{2}\)ab²

c) C= 2 a²b - 8b² + 5a²b + 5c^{2 -} 3b² + 4c²

Các cậu giúp mình với

Cảm ơn

Answer 1

a) \(A=5xy-3,5y^2-2xy+1,3xy+3x-2y\)

\(=\left(5xy-2xy+1,3xy\right)-3,5y^2+3x-2y\)

\(=-3,5y^2+4,3xy+3x-2y\)

b) \(B=\dfrac{1}{2}ab^2-\dfrac{7}{8}ab^2+\dfrac{3}{4}a^2b-\dfrac{3}{8}a^2b-\dfrac{1}{2}ab^2\)

\(=\left(\dfrac{1}{2}ab^2-\dfrac{7}{8}ab^2-\dfrac{1}{2}ab^2\right)+\left(\dfrac{3}{4}a^2b-\dfrac{3}{8}a^2b\right)\)

\(=-\dfrac{7}{8}ab^2+\dfrac{3}{8}a^2b\)

c) \(2a^2b-8b^2+5a^2b+5c^2-3b^2+4c^2\)

\(=\left(2a^2b+5a^2b\right)+\left(-8b^2-3b^2\right)+\left(5c^2+4c^2\right)\)

\(=7a^2b-11b^2+9c^2\)