Question

1. Verify that (-4, 12) is the solution to the system.
Show work to justify your answer

2x+y=5

-5x-2y=-6


2. Solve the system by graphing. State the solution.
x + y =2
2y – x = 10


3. Solve the system by substitution. State whether the
system has one solution, infinite solutions, or no
solution.
2x + y = 10
x – 3y = -2


Can someone please explain to me how to do these?

Answer 1

1.
substitute -4 for x and substitute 12 for y

2(-4) + 12 = 5 ??? NO WAY !!!!!

2. sketch graph
line one goes down from 2 on x axis at 45 degrees to right
line two goes from x = -10 when y = 0 up at 30 degrees to right
they hit at x = -2, y = 4

Answer 2

from first
y = (10-2x)
use in second
x - 3(10-2x) = -2

x - 30 + 6 x = -2
7 x = 28
x = 28/4 = 7
now go back and get y

Answer 3

1. plug -4 and 12 into both equations to confirm the solution

2. graph the two equations...the solution is the intersection of the lines
... there are several graphing programs online ... or you could use graph paper, ruler, and pencil

3. solve the 2nd equation for x, in terms of y
... substitute the value for x into the 1st equation

... solve for y, then solve for x

Answer 4

Thank you guys SO MUCH