Question

Solve the following system of equations algebraically for ALL values of x and y.
y=x^2+2x-8
y=2x+1

Answer 1

Before you start, can you think of how many x-values possibly are solution of this system?

Answer 2

3?

Answer 3

there are 2 solutions to x, since it is squared.

Answer 4

ok what do i do next?

Answer 5

try and eliminate one variable. y is the easiest to eliminate since you have two equations for y

Answer 6

ok now i have 0=x^2-9

Answer 7

factor that.

Answer 8

x= 3 or -3

Answer 9

yes....y should be very easy to find now

Answer 10

y=0?

Answer 11

y = 2x +1
plug in the values of x that you found

Answer 12

y=7

Answer 13

there are 2 solutions to y since there are 2 solutions to x.

Answer 14

y=7 and y=-7

Answer 15

no....
y = 2(3) + 1 = 7
y = 2(-3) + 1 = -5

Answer 16

oh ok thanks