Answer:
a) Height of the ledge is 1.6 m.
b) roots of the equation are: [tex]\bf d = 2[/tex] , [tex]\bf d = -1[/tex]
c) Maximum height reached = 1.8 m.
Step-by-step explanation:
a) The height of the ledge is the same as the height at which Jake is when he hasn't moved any horizontal distance from the ledge yet, that is, when d = 0:
[tex]h = -0.8(0)^2 + 0.8(0) + 1.6[/tex]
⇒ [tex]\bf h = 1.6 \space\ m[/tex]
∴ Height of the ledge is 1.6 m.
b) The x-intercepts occur where y = 0, that is when h = 0:
[tex]-0.8d^2 + 0.8d + 1.6 = 0[/tex]
Divide both sides of the equation by -0.8:
[tex]d^2 - d -2 = 0[/tex]
Factorizing:
⇒ [tex]d^2 -2d + d - 2 = 0[/tex]
⇒ [tex]d(d-2) +1 (d-2) = 0[/tex]
⇒ [tex](d-2)(d+1) = 0[/tex]
⇒ [tex]d - 2 = 0[/tex] or [tex]d + 1 = 0[/tex]
∴ roots are : [tex]\bf d = 2[/tex] , [tex]\bf d = -1[/tex]
c) To find the maximum value of a quadratic equation in the form
y = ax² + bx + c , use the formula:
max = c - (b² / 4a).
Using the formula for [tex]h = -0.8x^2 + 0.8x + 1.6[/tex] :
max h = [tex]1.6 - ( \frac{0.8^2}{4(-0.8)} )[/tex]
= 1.8
∴ Maximum height reached = 1.8 m.
