Question

y = 5x – 1
–15x – 3y = 3
How many solutions does this linear system have?

one solution: (0, –1)
one solution: (1, 4)
no solution
infinite number of solutions

Answer 1

y = 5x - 1...so we sub 5x - 1 in for y in the other equation

-15x - 3y = 3
-15x - 3(5x - 1) = 3
-15x - 15x + 3 = 3
-30x = 3 - 3
-30x = 0
x = 0

y = 5x - 1
y = 5(0) - 1
y = -1

it has one solution (0,-1) <=

Answer 2

y = 5x - 1...so we sub 5x - 1 in for y in the other equation

-15x - 3y = 3

-15x - 3(5x - 1) = 3

-15x - 15x + 3 = 3

-30x = 3 - 3

-30x = 0

x = 0

y = 5x - 1

y = 5(0) - 1

y = -1

it has one solution (0,-1) <=