Question

Solve system using substitution

3x+y=5
2x-5y=9

Answer 1

just for linear practice :)

3x+y=5
2x-5y=9

x = (9+25)/(2+15)
y = (27-10)/(-15-2)

maybe?

Answer 2

solve for one variable first:

i'm going to use the first equation:

3x+y=5
so y=-3x+5

plug that in to equation 2

2x-5(-3x+5)=9

2x+15x-25=9
17x-25=9
17x=34
x=2

plug that in:

3(2)+y=5
6+y=5
y= -1

so if all is correct, x=2, y=-1

Answer 3

trying to do a determinant backwards is tough

Answer 4

x = (9+25)/(2+15) = 34/17 = 2
y = (27-10)/(-15-2) = 17/-17 = -1

id say its right ;)

Answer 5

Thank you all! Life saved.