Question

solve using cross multiplication method x+y=3 2x+y=9​

Answer 1

Step-by-step explanation:

x+y=7 ----- (1)

2x−3y=9 ----- (2)

First use formula for cross multiplication method:

b

1

c

2

−b

2

c

1

x

=

c

1

a

2

−a

1

c

2

y

=

a

2

b

2

−a

2

b

1

−1

So, from equation (1) and (2) we can write the value of a, b and c.

1×9−(−3)×7

x

=

7×2−1×9

y

=

1×(−3)−2×1

−1

9+21

x

=

14−9

y

=

−3−2

−1

30

x

=

5

y

=

−5

−1

30

x

=

−5

−1

x=

−5

−30

=6

5

y

=

−5

−1

y=

−5

−5

y=1

Answer 2

x+y:2x+y::3:9

then,

solve using cross multiplication method x+y=3 2x+y=9