Question

if x=7 and y=3 is the solution of equations ax+by=18 and bx+ay=12 then a+b=___

Answer 1

Answer:

Step-by-step explanation:

It is given that

x=7 and y=3 ,ax+by=18,bx+ay=12

bx+ay=12

(b×7)+(a×3)=12

7b+3a=12

7b=12-3a

b=(12-3a)/7

Now putting the value of b in ax+by=18

(a×7)+(b×3)=18

7a+3b=18

7a+3((12-3a)/7)=18

7a+36-9a/7=18

36-9a+49a=18

36+40a/7=18

36+40a=18×7

36+40a=126

40a=126-36

40a=90

a=90/40

a=9/4

We know that b=(12-3a)/7

b=(12-3×9/4)/7

b=(12-27)/7×4

b=-15/28

Now putting the value of a and b in a+b

=9/4+(-15/28)

=9/4-15/28

=(63-15)/28

=48/28

=12/7

Answer 2

Answer:

3

Step-by-step explanation: