Question

The point (7, 8) is the solution of which of the following systems of equations?

1. 8x - y = 48
9x + 10y = 142

2. 9x - y = 55
8x + 10y = 140

3. x-6y=-41
8x + 9y = 127

4. x-7y=-49
10x + 9y = 142

Answer 1

4.

Explanation:

1. 8x - y = 48

9x + 10y = 142

8(7) - 8 = 48

9(7) + 10(8) = 143

No

2. 9x - y = 55

8x + 10y = 140

9(7) - 8 = 55

9(7) - 10(7) = -24

No

3. x-6y=-41

8x + 9y = 127

7 - 6(8) = -41

8(7) + 9(8) = 128

No

4. x-7y=-49

10x + 9y = 142

7 - 7(8) = 49

10(7) + 9(8) = 142

Yes

Answer 2

Option 4

Verification:-

`\\ \sf\longmapsto x-7y=-49`

`\\ \sf\longmapsto 7-7(8)=-49`

`\\ \sf\longmapsto 7-56=-49`

`\\ \sf\longmapsto -49=-49`

And

`\\ \sf\longmapsto 10x+9y=142`

`\\ \sf\longmapsto 10(7)+9(8)=142`

`\\ \sf\longmapsto 70+72=142`

`\\ \sf\longmapsto 142+142`

Hence verified