Solve u^2+3n-84=0

$$u ^ { 2 } + 3 n - 84 = 0$$

Solve for n

$$n=-\frac{u^{2}}{3}+28$$

Steps for Solving Linear Equation

Subtract u^{2} from both sides. Anything subtracted from zero gives its negation.

$$3n-84=-u^{2}$$

Add 84 to both sides.

$$3n=-u^{2}+84$$

The equation is in standard form.

$$3n=84-u^{2}$$

Divide both sides by 3.

$$\frac{3n}{3}=\frac{84-u^{2}}{3}$$

Dividing by 3 undoes the multiplication by 3.

$$n=\frac{84-u^{2}}{3}$$

Divide -u^{2}+84 by 3.

$$n=-\frac{u^{2}}{3}+28$$

Solve for u (complex solution)

$$u=-\sqrt{84-3n}$$

$$u=\sqrt{84-3n}$$

Solve for u

$$u=\sqrt{84-3n}$$

$$u=-\sqrt{84-3n}\text{, }n\leq 28$$