Question

Solve the following systems of equations by elimination method:
1. 3x + 4y = -6 3x - y = 9

Answer 1

Answer:

3x−5y−4=0 and 9x=2y+7

3x−5y−4=0,

3x−5y=4.. .... ...(i)

9x=2y+7,

9x−2y=7.. .... ..(ii)

Multíplying éqn (i) by 3

9x−15y=12.. ... ...(iii)

subtràct éqn (iii) fróm (ii)

13y= −5

y= − 13

5 Pút in éqn (i)

3x−5× 13−5 =4

Multíplying by 13 on both side

39x+25=52

39x=27

9

x= 13

Answer 2

Answer:

3x−5y−4=0 and 9x=2y+7

3x−5y−4=0,

3x−5y=4.. .... ...(i)

9x=2y+7,

9x−2y=7.. .... ..(ii)

Multíplying éqn (i) by 3

9x−15y=12.. ... ...(iii)

subtràct éqn (iii) fróm (ii)

13y= −5

y= − 13

5 Pút in éqn (i)

3x−5× 13−5 =4

Multíplying by 13 on both side

39x+25=52

39x=27

9

x= 13