Bring x = 3 into the equation and get m =-13. Bring m =-13 back to the equation, and the other root of the solution is -2/5.

You can also use the relationship between roots and coefficients, assuming that X 1 and X2 are the two roots of the equation ax 2+bx+c = 0, there are

1) X 1*X2 = c/a

2) X 1+X2 = -b/a

In your topic, it is 3 * x2 =-6/5 and 3+x2 =-m/5. The above answers can also be obtained by solving these two equations separately. (But the following one is much faster. )