4x-9y=9 -x+3y=6 Rewrite one of the two equations above in the form ax + by = c, where a, b, and c are constants, so that the sum of the new equation and the unchanged equation from the original system results in an equation in one variable.

Respuesta :

Answer:

the rewritten equation

[tex]-4x+12y=24[/tex]

the equation in one variable:

[tex]3y=33[/tex]

the solution for the system:

[tex]y=11, x=27[/tex]

Step-by-step explanation:

system of equations is:

[tex]4x-9y=9 \\-x+3y=6[/tex]

If we multiply the second equation by 4, we can rewrite it like this:

[tex]4(-x+3y=6)\\-4x+12y=24[/tex]

this last equation has the form [tex]ax+by=c[/tex]

so now we sum this equation to the unchanged equation:

[tex]4x-9y=9\\-4x+12y=24\\--------------------\\0x +3y=33\\[/tex]

we get the equation with one variable [tex]3y=33[/tex].

If you need to solve the whole system, we clear for y in the last equation:

[tex]y=33/3\\y=11[/tex]

and using the first original equation we subtitute [tex]y[/tex] to find [tex]x[/tex]

[tex]4x-9(11)=9\\4x-99=9\\4x=9+99\\4x=108\\x=108/4\\x=27[/tex]