Composition book out You need graph paper! Engage your brains! Here we go Composition book out You need graph paper! Engage your brains!

7.1 solving linear systems by graphing When you solve a problem that has 2 or more equations, it is called a system of linear equations or a linear system. A solution of a linear systems w/2 variables is an ordered pair (x,y) that satisfies both equations. One answer that works for both equations. When the equations of a linear systems are graphed, the solution is the point at which they intersect.

Checking a solution algebraically Check that (2, -1) is a solution of the system 3x + 2y = 4 -x + 3y = -5 Is (2, -1) a solution to the linear system? yes

Joke of the day! A cannibal entered the meat market to buy something nice for dinner. The owner greeted him and told him to look around. The cannibal began to inspect the meat case and noticed the market specialized in brain. Upon further inspection he noticed a marked disparity between the costs of brain meats. A carpenter's brain sells for $1.50 per pound. A plumber's brain sells for $2.25 per pound. He noticed with alarm that a politician's brain sells for $375.00 a pound. With not a little curiosity he asked the owner why the huge difference in price between the similar meats. The owner responded with a deadpan look on his face, Do you realize how many politicians it takes to get a pound of brains?"

Solving a linear system by graphing & checking To find the answer, you must graph the 2 equations on the same graph & find the point where they intersect. To solve by graphing: Write both equations in slope-intercept form Graph check by substituting

Solving linear system by graphing X + y = -2 2x – 3y = -9 Solution (-3, 1)

Graph to find the solution 2x – y = 8 -x + 2y = -1 Answer (5,2)

Is (-3, 1) a solution of the following system? Try these Is (-3, 1) a solution of the following system? -4x + 5y = 17 9x + y = -17 Answer no

Questions?