1) 4х - 4у + 20 = 0

4х - 3у + 10 = 0

4х - 4у + 20 = 0

4х = 3у - 10

3у - 10 - 4у + 20 = 0

у = 10

4х = 3 × 10 - 10

х = 5

( х ; у ) = ( 5 ; 10 )

4 × 5 - 4 × 10 + 20 = 0

4 × 5 - 3 × 10 + 10 = 0

0 = 0

0 = 0

( х ; у ) = ( 5 ; 10 )

2) 3х - 2у - 7 = 0

5х - 3у - 14 =0

х = 2/3 у + 7/3

5х - 3у - 14 = 0

5 × ( 2/3 у + 7/3 ) - 3у - 14 = 0

у = 7

2/3 × 7 + 7/3

х = 7

( х ; у ) = ( 7 ; 7 )

3 × 7 - 2 × 7 - 7 = 0

5 × 7 - 3 × 7 - 14 = 0

0 = 0

0 = 0

( х ; у ) = ( 7 ; 7 )