Write three more equations with integer coefficients and the variable x that have the same solution set {7, - 1}. Explain.

The given values of abscissa and ordinate in the given are that which when substituted to the values of x and y in the equation will make the equation true. This means that the left and right-hand side of the equation will be equal. The established equations should have a basis of,

x + y = c

The equations are,

x + y = 6

Substituting x = 7 and y = - 1,

7 + (-1) = 6; 6 = 6

The other two equations will be,

2x + y = 13 and,

x + 2y = 5

It is to be noted that countless of equations can be made with the given solution so long as the equation is valid.