Solve {l}{x=4}{y=5}{z={(-3y)}{(xy+y^2)}}{text{Solvefor}atext{where}}{a=z}

$$\left. \begin{array} { l } { x = 4 }\\ { y = 5 }\\ { z = {(-3 y)} {(x y + y ^ {2})} }\\ { \text{Solve for } a \text{ where} } \\ { a = z } \end{array} \right.$$

Solve for x, y, z, a

$$a=-675$$

Solution Steps

Consider the third equation. Insert the known values of variables into the equation.

$$z=-3\times 5\left(4\times 5+5^{2}\right)$$

Multiply -3 and 5 to get -15.

$$z=-15\left(4\times 5+5^{2}\right)$$

Multiply 4 and 5 to get 20.

$$z=-15\left(20+5^{2}\right)$$

Calculate 5 to the power of 2 and get 25.

$$z=-15\left(20+25\right)$$

Add 20 and 25 to get 45.

$$z=-15\times 45$$

Multiply -15 and 45 to get -675.

$$z=-675$$

Consider the fourth equation. Insert the known values of variables into the equation.

$$a=-675$$

The system is now solved.

$$x=4 y=5 z=-675 a=-675$$