Question

solve for X & Y by substitution method
3x+4y = 2 and 5x+7y=0
step by step explanation​

Answer 1

Answer

y=-10,x=14

Explanation

3x+4y=2 _1

5x+7y=0 _2

taking value of x from equation 2

x=-7y/5 _3

put x=-7y/5 in equation 1

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

-21y/5+4y=2

taking L.C.M., we get

-1y/5=2

y=-10

put y=-10 in equation 3

x=-7(-10)/5

x=70/5

x=14

Answer 2

Answer:

x= 14, y=(-10)

Step-by-step explanation:

5x +7y =0

x= (-7y )/5 ---------(i)

substituting eq (i) in 3x+4y = 2

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

-21y/5 + 20y/5 =2

-21y +20y = 10

-y= 10

y=(-10)--------------(ii)

now substituting eq(ii) in eq(i)

x=  -7* -10 /5  = 14

x= 14

(Tip always substitute bigger eq in smaller one to make calculation easier)