Question

(-2x+3y=8....(i)
( x+y=2.........(ii)
solve by elumination method and substitution​

Answer 1

Answer:

 x = -2/5

 y = 12/5

Step-by-step explanation:

Substitution method;

-2x + 3y = 8  -----------(i)

x + y =2   -----------(ii)

x = 2 - y

substitute the value of x in equ (i)

  (-2)* (2-y) + 3y = 8

     -4 + 2y + 3y = 8

                   5y = 8 + 4

                     y = 12/5

substitute the value of y in equ (ii)

x + 12/5 = 2

        x = 2 - 12/5

           = 2*5/1*5 - 12/5  

          = 10 -12/5 = -2/5

Ans: x = -2/5

       y = 12/5

elimination method:

-2x + 3y = 8  -----------(i)

x + y =2   -----------(ii)

                                    (i)   ====>    -2x + 3y = 8

multiply equ (ii) by 2         ====>      2x + 2y = 4

             add (i) and (ii)                             5y = 12

                                                                   y = 12/5

Substitute in equ (ii)

x + 12/5 = 2

        x = 2 - 12/5

           = 2*5/1*5 - 12/5  

          = 10 -12/5 = -2/5

Ans: x = -2/5

       y = 12/5

                                                       

               

Answer 2

ELIMINATION:

You can multiply the second equation by 2:

$\begin{cases}-2x+3y=8\\2x+2y=4\end{cases}$

And then add the two equations:

$(-2x+3y)+(2x+2y)=8+4 \iff 5y=12 \iff y=\dfrac{12}{5}=2.4$

And we deduce

$x=2-y = 2-2.4=-0.4$

SUBSTITUTION:

From the second equation, we derive

$x=2-y$

Plug this expression for x in the first equation:

$-2x+3y=8 \iff -2(2-y)+3y=8 \iff -4+2y+3y=8 \iff 5y=12$

And from here you proceed in the same way as above.