Question

Solve for x and y simultaneously:x+y=8 and 3x+2y=21

Answer 1

Answer:

3x+4y =14----(1)

5x+2y=21-----(2)

multiply (2) with 2 and subtract (1) from it

10x+4y=42

3x+4y=14

__________

7x=28

x=28/7

x=4

plug x=4 in (1)

3*4+4y=14

12+4y =14

4y=14-12

4y =2

y =2/4

y=1/2

therefore

x=4,y=1/2

Step-by-step explanation:

Answer 2

Answer:

x+y=8

Step-by-step explanation:

3(x+y-8)=0

3x+3y-24=0

subtraction of 2nd equation

3x+3y-24=0

3x+2y-21=0

=y-3=0

y=3

put y in 1st equation

x+3=8

x=8-3

x=5