Question

Solve 2x + y = 7
x – y = –4

Answer 1

add bouth equations:
2x + y = 7
x – y = –4
----------- +
3x =3
x=1
1-y=-4
y=5

Answer 2

given.
2x + y = 7 ...............1
x - y = - 4
=>x = y - 4 ................2
Now put this value of x in equation 1.
2 ( -4 + y ) + y =7
=>-8 + 2y + y = 7
=>3y =15
=>y = 5

Now put this value of y in equation 2.
x= 5 - 4
=>x = 1

(x,y) = (1,5)

Answer 3

then how woul i do this one ??
What is a possible first step to eliminate a variable in the following system?
7x – 9y = 2
3x – 6y = –4

Answer 4

<<7x-9y=2

<<3x-6y=-4

When doing elimination the idea is to get one of the variables to cancel out.

2(7x-9y)=2(2) = 14x-18y=4 [first equation]

-3(3x-6y)=-3(-4) = -9x+18y=-12 [second equation]

You'll notice that the y's in this case cancel each other out.

Multiply the first equation by 2 and the second equation by -3 <<<<Answer

Answer 5

thats what i got too(: