For what value of m would the functions f(x)= −mx +5 and g(x)= mx^2−4x +1 have exactly one point of intersection?

Question

For what value of m would the functions f(x)= −mx +5  and g(x)= mx^2−4x +1  have exactly one point of intersection?

help

oobleck · Answer

that would be when the equation −mx +5 = mx^2−4x +1 has exactly one root. That is, when the discriminant is zero mx^2 + (m-4)x - 4 = 0 (m-4)^2 + 16m = 0 m = -4