Meera throws a ball upward. Its height (m) after t seconds is h = -5t^2 + 10t + 2. To check whether the ball ever reaches a height of 7 m, she sets -5t^2 + 10t + 2 = 7. What does the discriminant tell about the number of times it reaches 7 m?

Question

Accepted Answer

Reaches it at exactly one time (D = 0). -5t^2 + 10t + 2 = 7 gives -5t^2 + 10t - 5 = 0, i.e. 5t^2 - 10t + 5 = 0, or t^2 - 2t + 1 = 0. D = 4 - 4 = 0, so the ball reaches 7 m at exactly one time (the peak).

Meera throws a ball upward. Its height (m) after $t$ seconds is $h = - 5 t^{2} + 10 t + 2$ .
To check whether the ball ever reaches a height of 7 m, she sets $- 5 t^{2} + 10 t + 2 = 7$ .
What does the discriminant tell about the number of times it reaches 7 m?

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More Class 10 Nature of Roots (Discriminant) practice

Meera throws a ball upward. Its height (m) after t seconds is h=−5t2+10t+2.To check whether the ball ever reaches a height of 7 m, she sets −5t2+10t+2=7.What does the discriminant tell about the number of times it reaches 7 m?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 Nature of Roots (Discriminant) practice

Meera throws a ball upward. Its height (m) after $t$ seconds is $h = - 5 t^{2} + 10 t + 2$ .
To check whether the ball ever reaches a height of 7 m, she sets $- 5 t^{2} + 10 t + 2 = 7$ .
What does the discriminant tell about the number of times it reaches 7 m?