## DragonFlame one year ago Solve, using the substitution method. y – 2x = 8 16 + 4x = 2y

1. hartnn

y-2x = 8 add 2x on both sides, what u get ?

2. DragonFlame

y=9+2y

3. hartnn

now plug in y= 8+2x in 2nd equation

4. DragonFlame

I thought of doing -2x=8-y

5. hartnn

that can work, but things will get complicated soon.

6. DragonFlame

16+4x=2(8+2x)

7. DragonFlame

I see... I will use the way u told me than

8. hartnn

yes, simplify 2(8+2x)

9. DragonFlame

16+4x=16+4x

10. DragonFlame

O.O IMPOSSIBLE

11. hartnn

correct. now think logically, when is that true

12. hartnn

not impossible its like 0=0

13. DragonFlame

S0 infinite number of solutions

14. hartnn

you take any value of x or y 16+4x will always be = 16+4x so, yes, infinite solutions :)

15. DragonFlame

yay! Thanks so much

16. mathmale

Note how one of the given equations is a multiple of the other given equation. That's all the info you need to decide "infinitely many solutions."

17. DragonFlame

I see, Thanks :)

18. mathmale

:)