Question

Solve the following system of equations by substitution. Show all steps.

Answer 1

Answer:

Given system of equations:

$\begin{cases}f(x)=-x^2+2x+3\\g(x)=-2x+3\end{cases}$

To solve by substitution, equate the equations and solve for x:

$\begin{aligned}f(x) & = g(x)\\\implies -x^2+2x+3 & = -2x+3\\-x^2+4x & = 0\\x^2-4x & = 0\\x(x-4) & = 0\\\implies x & = 0\\\implies x-4 & = 0 \implies x=4\end{aligned}$

Therefore, the x-values of the solution are $x = 0$ and $x = 4$.

To find the y-values of the solution, substitute the found values of x into the functions:

$f(0)=-(0)^2+2(0)+3=3$

$g(0)=-2(0)+3=3$

$f(4)=-(4)^2+2(4)+3=-5$

$g(4)=-2(4)+3=-5$

Therefore, the solutions to the given system of equations are:

$(0, 3)$ and $(4, -5)$