We know that
the equation of the parabola is of the form
y=ax²+bx+c
in this problem
y=1/4x²−x+3
where
a=1/4
b=-1
c=3
the coordinates of the focus are
(-b/2a,(1-D)/4a)
where D is the discriminant b²-4ac
D=(-1)²-4*(1/4)*3-----> D=1-3---> D=-2
therefore
x coordinate of the focus
-b/2a----> 1/[2*(-1/4)]----> 2
y coordinate of the focus
(1-D)/4a------> (1+2)/(4/4)---> 3
the coordinates of the focus are (2,3)
Given:
bottom of the plank or ground is 9 feet from the wall
length of the plant is 41 ft
height of the wall is unknown.
Let us use the Pythagorean theorem.
a² + b² = c²
a² + (9ft)² = (41ft)²
a² + 81 ft² = 1,681 ft²
a² = 1,681 ft² - 81 ft²
a² = 1,600 ft²
√a² = √1,600 ft²
a = 40 ft
The height of the wall is 40 ft.
74....74....74............
Answer: b)
Step-by-step explanation:
3^3 is equal to 27 exactly, but it asks for an approximate. 27.55 is near 27 so yea, there ya go ^
