Question

Cho hai đa thức :A(x) = 3x² - 2x⁴ + 5x⁵ + 2x - 7 - x⁵ + 3x

B(x) = -3x⁴ + 3x + x² - 4x⁵ + 5x⁴ - x - 12

a)thu gon các đa thức A(x) và B(x)

b) tính A(x) +B(x); A(x) - B(x)

Answer 1

a) \(A\left(x\right)=4x^5-2x^4+3x^2+5x-7\)

\(B\left(x\right)=-4x^5+2x^4+x^2+2x-12\)

hơi lười :((

b) \(A\left(x\right)+B\left(x\right)\\ =\left(4x^5-2x^4+3x^2+5x-7\right)+\left(-4x^5+2x^4+x^2+2x-12\right)\\ =4x^5-2x^4+3x^2+5x-7-4x^5+2x^4+x^2+2x-12\\ =\left(4x^5-4x^5\right)+\left(-2x^4+2x^4\right)+\left(3x^2+x^2\right)+\left(5x+2x\right)+\left(-7-12\right)\\ =4x^2+7x-19\)

\(A\left(x\right)-B\left(x\right)\\ =\left(4x^5-2x^4+3x^2+5x-7\right)-\left(-4x^5+2x^4+x^2+2x-12\right)\\ =4x^5-2x^4+3x^2+5x-7-4x^5-2x^4-x^2-2x+12\\ =\left(4x^5-4x^5\right)+\left(-2x^4-2x^4\right)+\left(3x^2-x^2\right)+\left(5x-2x\right)+\left(-7+12\right)\\ =-4x^4+2x^2+3x+5\)