Cho 2 đa thức: f(x)=2x^4+5x^3-x-8 g(x)=x^4-x^2+3x+9 Tìm đa thức h(x) sao cho: a) f(x)-g(x)=h(x) b) h(x)-g(x)=f(x)

$\text{a) f(x) - g(x) = h(x)}$

$\text{(2$x^{4}$ + 5x³ - x - 8) - ($x^{4}$ - x² + 3x + 9) = h(x)}$

$\text{2$x^{4}$ + 5x³ - x - 8 - $x^{4}$ + x² - 3x - 9 = h(x)}$

$\text{(2$x^{4}$ - $x^{4}$) + 5x³ + x² + (-x - 3x) + (-8 - 9) = h(x)}$

$\text{$x^{4}$ + 5x³ + x² - 4x - 17 = h(x)}$

$\text{Vậy h(x) = $x^{4}$ + 5x³ + x² - 4x - 17}$

$\text{b) h(x) - g(x) = f(x)}$

$\text{h(x) = f(x) + g(x)}$

$\text{h(x) = (2$x^{4}$ + 5x³ - x - 8) + ($x^{4}$ - x² + 3x + 9)}$

$\text{h(x) = 2$x^{4}$ + 5x³ - x - 8 + $x^{4}$ - x² + 3x + 9}$

$\text{h(x) = (2$x^{4}$ + $x^{4}$) + 5x³ - x² + (-x + 3x) + (-8 + 9)}$

$\text{h(x) = 3$x^{4}$ + 5x³ - x² + 2x + 1}$

$\text{Vậy h(x) = 3$x^{4}$ + 5x³ - x² + 2x + 1}$

$\textit{Ha1zzz}$