Choose One to Do Now:
Solve the system of equations by graphing:
{
y=x+7
2x + y = - 2
OR
{
x - y = -7
6x + 3y = -6
Today you will
solve systems of equations
by using substitution
or
by using elimination
6.2
Solving Systems by Substitution
{
y=x+7
2x + y = - 2
{
x = 2y - 4
x + 8y = 16
{
4x + y = 6
y = x+1
{
2x - y = 8
y = 2x - 3
6-3 and 6-4
Solving Systems by Elimination
8 + 2 = 10
8 + 2 = 10
7-4 =
7-4 =
3
3
{
x + 4y = 23
-x + y =
2
{
2x + y = -4
x + y = -7
+ 2y = 0
{ -4x
10x + 3y = 8
{
4x - 3y = 1
6y - 8x = -2
800 people came to the school play. The
ratio of adults to children was 3 to 2.
Write a system of equations to find the
number of adults and the number of
children who came to the play.