Question

When Raphael solved the system below by using the method of elimination, he changed the second equation to -8x-2y=-2 what property justifies this manipulation?
8x+3y=7
4x+y=1

Answer 1

For this case, what we are going to do is use the following property:
 Multiply an equation by a scalar.
 In this case, the scalar will be:
 k = -2
 We have then that equation 2 will be:
 k * (4x + y) = k * 1
 -2 * (4x + y) = - 2 * 1
 -8x-2y = -2
 Answer:
 The property that justifies this manipulation is:
 Multiply an equation by a scalar.