91Ó°ÊÓ

Graph the solution set of each system of inequalities, when possible. If not possible, state \(0 .\) SEE EXAMPLE 8. (OBJECTIVE 4) $$\left\\{\begin{array}{l}y<2 x-1 \\\2 x-y<-4\end{array}\right.$$

Use elimination to solve each system. $$\left\\{\begin{array}{l}2 x-7 y=10 \\\2 x=7 y-10\end{array}\right.$$

Use two equations in two variables to solve each application. A merchant wants to mix peanuts worth \(\$ 3\) per pound with jelly beans worth \(\$ 1.50\) per pound to make 30 pounds of a mixture worth \(\$ 2.10\) per pound. How many pounds of each should he use?

Use elimination to solve each system. $$\left\\{\begin{array}{l}10 x=2 y+12 \\\6=5 x-y\end{array}\right.$$

Determine whether the pair is a solution of the system. $$\left(-\frac{2}{5}, \frac{1}{4}\right),\left\\{\begin{array}{l} 5 x-4 y=-6 \\ 8 y=10 x+12 \end{array}\right.$$

Graph the solution set of each system of inequalities, when possible. If not possible, state \(0 .\) SEE EXAMPLE 8. (OBJECTIVE 4) $$\begin{aligned}&y \leq-\frac{4}{3} x-2\\\&4 x+3 y>15\end{aligned}$$

Use two equations in two variables to solve each application. A high- efficiency \(90+\) furnace costs $$ 2,250\( and costs an average of $$ 412\) per year to operate in Rockford, IL. An \(80+\) furnace costs only $$ 1,715\( but costs $$ 466\) per year to operate. Find the break-even point.

Use substitution to solve each system. $$\left\\{\begin{array}{l}r+3 s=9 \\\3 r+2 s=13\end{array}\right.$$

Graph the solution set of each system of inequalities, when possible. If not possible, state \(0 .\) SEE EXAMPLE 8. (OBJECTIVE 4) $$\left\\{\begin{array}{l}3 x+y<-2 \\\y>3(1-x)\end{array}\right.$$

Use substitution to solve each system. $$\left\\{\begin{array}{l}x-2 y=2 \\\2 x+3 y=11\end{array}\right.$$