Løs 1/x^2-1-2/x^2+3x-4+1/x^2-2x-3

$$\frac { 1 } { x ^ { 2 } - 1 } - \frac { 2 } { x ^ { 2 } + 3 x - 4 } + \frac { 1 } { x ^ { 2 } - 2 x - 3 }$$

Evaluer

$$\frac{2\left(4x-5\right)}{\left(x-3\right)\left(x+4\right)\left(x^{2}-1\right)}$$

Korte løsningstrin

Faktoriser x^{2}-1. Faktoriser x^{2}+3x-4.

$$\frac{1}{\left(x-1\right)\left(x+1\right)}-\frac{2}{\left(x-1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

For tilføje eller fratrække udtryk skal du udvide dem for at gøre nævneren ens. Mindste fælles multiplum for \left(x-1\right)\left(x+1\right) og \left(x-1\right)\left(x+4\right) er \left(x-1\right)\left(x+1\right)\left(x+4\right). Multiplicer \frac{1}{\left(x-1\right)\left(x+1\right)} gange \frac{x+4}{x+4}. Multiplicer \frac{2}{\left(x-1\right)\left(x+4\right)} gange \frac{x+1}{x+1}.

$$\frac{x+4}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}-\frac{2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Eftersom \frac{x+4}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} og \frac{2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} har den samme fællesnævner, kan du trække dem fra dem ved at trække deres tællere fra.

$$\frac{x+4-2\left(x+1\right)}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Lav multiplikationerne i x+4-2\left(x+1\right).

$$\frac{x+4-2x-2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Kombiner ens led i x+4-2x-2.

$$\frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{x^{2}-2x-3}$$

Faktoriser x^{2}-2x-3.

$$\frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{1}{\left(x-3\right)\left(x+1\right)}$$

For tilføje eller fratrække udtryk skal du udvide dem for at gøre nævneren ens. Mindste fælles multiplum for \left(x-1\right)\left(x+1\right)\left(x+4\right) og \left(x-3\right)\left(x+1\right) er \left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right). Multiplicer \frac{-x+2}{\left(x-1\right)\left(x+1\right)\left(x+4\right)} gange \frac{x-3}{x-3}. Multiplicer \frac{1}{\left(x-3\right)\left(x+1\right)} gange \frac{\left(x-1\right)\left(x+4\right)}{\left(x-1\right)\left(x+4\right)}.

$$\frac{\left(-x+2\right)\left(x-3\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}+\frac{\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Da \frac{\left(-x+2\right)\left(x-3\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)} og \frac{\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)} har den samme fællesnævner, skal du addere dem ved at tilføje deres tællere.

$$\frac{\left(-x+2\right)\left(x-3\right)+\left(x-1\right)\left(x+4\right)}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Lav multiplikationerne i \left(-x+2\right)\left(x-3\right)+\left(x-1\right)\left(x+4\right).

$$\frac{-x^{2}+3x+2x-6+x^{2}+4x-x-4}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Kombiner ens led i -x^{2}+3x+2x-6+x^{2}+4x-x-4.

$$\frac{8x-10}{\left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right)}$$

Udvid \left(x-3\right)\left(x-1\right)\left(x+1\right)\left(x+4\right).

$$\frac{8x-10}{x^{4}+x^{3}-13x^{2}-x+12}$$

Differentier w.r.t. x

$$\frac{2\left(43-130x+67x^{2}+12x^{3}-12x^{4}\right)}{\left(\left(x-3\right)\left(x+4\right)\left(x^{2}-1\right)\right)^{2}}$$