Question

Solve for and ; 7 − 4 = 49 and 5 − 6 = 57​

Answer 1

Explanation:

We have,

7x−4y=49...(i) and

5x−6y=57...(ii)

Here

a

1

=7,b

1

=−4,c

1

=49 and

a

2

=5,b

2

=−6,c

2

=57

So,

a

2

a

1

=

5

7

,

b

2

b

1

=

−6

−4

=

3

2

Since,

a

2

a

1



=

b

2

b

1

The system has a unique solution.

Now, Multiply equation (i) by 5 and equation (ii) by 7 and subtract,

35x−20y=245

35x−42y=399

22y=−154

⇒y=−7

Put y=−7 in equation (ii)

5x−6(−7)=57

⇒5x=57−42

⇒x=3

Hence x=3 and y=−7