Question 361966
using elimination, the best first step is multiply the first equation by -3.


multiply the second equation by 3 doesn't do anything to eliminate one of the unknowns.


solving for x in the first equation or solving for y in the second equation are the substitution method, not the elimination method.


your original equations are:


x  - 5y = 4
3x + 7y = -17


multiply the first equation by -3 to get:


-3x + 15y = -12
3x + 7y = -17


add both equations together to get:


22y = -29


divide both sides of the equation by 22 to get:


y = (-29/22)


substitute in first original equation to get:


x - 5y = 4 becomes x - 5 * (-29/22) = 4 becomes x - (-145/22) = 4 becomes x + (145/22) = 4.


subtract (145/22) from both sides of the equation to get:


x = 4 - (145/22) which becomes x = (88/22) - (145/22) which becomes x = (-57/22)


your solutions are:


x = (-57/22)


y = (-29/22)


substitute for x and y in both original equations and you will see that they are both true which means the solution is good.


the equations being true means that the left side of the equation is equal to the right side of the equation.