Question

-2x + 4y = 48

x + 4y = 24
A.
x = -8, y = 8
B.
x = 8, y = -8
C.
x = 2, y = 13
D.
x = 8, y = 4

Answer 1

A

Explanation:

Given the 2 equations

- 2x + 4y = 48 → (1)

x + 4y = 24 → (2)

Subtracting (2) from (1) term by term will eliminate the y- term, that is

- 3x = 24 ( divide both sides by - 3 )

x = - 8

Substitute x = - 8 into either of the 2 equations and solve for y

Substituting in (2)

- 8 + 4y = 24 ( add 8 to both sides )

4y = 32 ( divide both sides by 4 )

y = 8

Solution is x = - 8, y = 8 → A

Answer 2

x=-8

y=8

Explanation:

-2x+4y=48...(1)

x+4y=24....(2)

From (2) make x the subject of formula

x=24-4y....(3)

Substitute (3) into (1)

-2(24-4y)+4y=48

-48+8y+4y=48

Add 48 to both sides

8y+4y=48+48

12y=96

Divide both sides by 12

y=8

Substitute y=8 into (1)

-2x+4(8)=48

-2x+32=48

-2x=48-32

-2x=16

Divide both sides by _2

X=-8

Therefore x=-8 and y=8