150 likes | 329 Views
Bellwork. Solve the system 2x+3y=-9 x-2y=6 You buy 8 pencils for $8 at the bookstore. Standard pencils cost $.85 and specialty pencils cost $1.25. How many specialty pencils did you buy?. Example. Solve the system 2x+3y=-9 x-2y=6. Example.
E N D
Bellwork • Solve the system • 2x+3y=-9 x-2y=6 • You buy 8 pencils for $8 at the bookstore. Standard pencils cost $.85 and specialty pencils cost $1.25. How many specialty pencils did you buy?
Example • Solve the system • 2x+3y=-9 x-2y=6
Example You buy 8 pencils for $8 at the bookstore. Standard pencils cost $.85 and specialty pencils cost $1.25. How many specialty pencils did you buy?
Solve Special Types of Linear Systems Section 7.5
The Concept • Since discussing linear systems, we’ve created a quiver of methods for solving: Graphing, Substitution and Elimination • Today we’re going to talk about some special kinds of systems
Vocabulary • Inconsistent System • A system of equations in which no point of intersection exists • These lines are Parallel • Consistent System • A system of equations in which all solutions to both equations serve as solutions to the other • These systems have infinitely many solutions • They are in fact the same lines
Example Let’s do an example 5y+1x=9 5y=-x+13
Example Let’s do an example 2y+2x=12 x=-y+6
Findings • If lines are parallel, then they will never intersect and are inconsistent • Parallel lines have the same slope but different y-intercepts • Lines with the same slopes and the same y-intercepts are consistent • Lines with different slopes, regardless of the y-intercept intersect with 1 solution
The Rules • Different slopes • 1 solution • Same Slopes, Different Y-Intercept • No Solutions, Inconsistent • Same Slopes, Same Y-Intercept • Infinitely Many Solutions, Consistent
Example • Without solving the linear system, tell whether the linear system has one solution, no solution or infinitely many solutions.
Homework • 7.5 • 2-14 even, 24-32 even, 36, 39
Practical Practice • A pizza parlor fills two pizza orders. Find the cost of one medium pizza
Most Important Points • Systems of equations sometimes have no solutions or infinitely many solutions • Definition of an inconsistent and consistent system • Rules for knowing the number of solutions