Help! Can anyone solve this equation by using the substitution method?

Question

2x + 5y = 7
x + 4y = 2

Thanks.

Answer 1

Sure -- Try this

2x + 5y =7
x + 4y =2

Mutiply the bottom equation by 2.

2x + 5y =7
2x + 8y = 4

Now subtract the second from the first

-3y = 3
y = -1

Now substitute in the first equation

2x + 5(-1) =7
2x -5 =7
2x = 12
x = 6

So answer is x =6, y= -1.

Check

Second equation:
6 + 4(-1) =2 ??
6 -4 = 2??
2=2 YES!!

Hope this helps.

Answer 2

take x+4y =2
----- x =2-4y-------(1)
now substitute value of x in 2x+5y=7
we get 2(2-4y)+5y =7
---- 4 - 8y +5y=7
----- (-3y)=7-4
-------(-3y)=3
-------y=3/ (-3)
-------y = -1
now substitute value of y in equation (1) that is x=2-4y
x=2-4(-1)
x=2+4
x=6

therefore answer is x=6 and y= -1
you can verify the answer by plugging in the value of x and y in any of the 2 main equations
ALL THE BEST


the method that first person told in wich he multiplied by 2 is called equating d coefficients and then substituting

Answer 3

2x+5y=7 2(2-4y)=7
x+4y=2 4-8y=7
-4 -4
x+4y=2 -8y=3
-4y -4y y=-3/8
x=2-4y

x=2-4(-3/8)
x=2+12/8
x=28/8 or 3 and 1/2

Answer 4

2x + 5y = 7 ---(1)
x + 4y = 2---- (2)

x=2-4y substitue for x in eqn (1)

2(2-4y)+5y =7
4-8y+5y=7
-3y=3
y= -1

sub y value in eqn(2)
x-4=2
x=6 ; y= -1

Answer 5

x = 2 - 4y

4 - 8y + 5y = 7
- 3y = 3
y = - 1

x - 4 = 2
x = 6

x = 6 , y = - 1

Answer 6

the one who answered first is right.