Question

SAT subject test question:
If 25x^2-20k+k=0 has 2/5 as a double root, k=?

Answer 1

now it says that 2/5 is a double root i.e. the roots are 2/5, 2/5.

simply substitute x = 2/5 in the equation.

Answer 2

oh, so if the double roots are given, you just need to plug them in to "x"?

Answer 3

ROOT or SOLUTION means any value of X which will make the answer of equation equal to 0.

so yes u just need to plug in the value of x

Answer 4

Thank you!