Question

4x + 8y=20 3x+6y=15 solve this system of equations

Answer 1

4x=20-8y

x=5-2y now use this value of x in the second equation...

3(5-2y)+6y=15

15-6y+6y=15

15=15  This is true for any y or x value.

So there are infinitely many solutions as the two equations describe the same line.

Answer 2

$4x + 8y=20 \ \ \ \ \ : \ \ \ \ \ 3x+6y=15$ 

$\text{Solve for x in 4x+8y=20}$ 

$4x+8y=20$ 

$4(x+2y)=20$ 

$x+2y= \dfrac{20}{4}$ 

$x+2y=5$ 

$x=5-2y$ 

$15=15$ 

$\text{Infinitely Many Solutions}$