Question
For what values of m does the graph of y = mx^2 – 5x – 2 have no x-intercepts?
For what values of m does the graph of y = mx^2 – 5x – 2 have no x-intercepts?
The x-intercepts of a parabola occur when y = mx² – 5x – 2 equals zero. Therefore, we need to solve the equation:
mx² – 5x – 2 = 0
For the graph of the equation to have no x-intercepts, the discriminant "b² - 4ac" must be less than zero (since a and b are both non-zero in this equation). The discriminant of this quadratic equation is:
b² - 4ac = (-5)² - 4(m)(-2) = 25 + 8m
For the equation to have no x-intercepts, we need:
25 + 8m < 0
Subtracting 25 from both sides of the inequality gives:
8m < -25
Dividing both sides by 8 (remembering to flip the inequality since we are dividing by a negative number) gives:
m > -25/8
Therefore, for values of m greater than -25/8, the graph of y = mx² – 5x – 2 has no x-intercepts.