Equation of the parabola: y = ax^2 + bx + c. Find a, b, and c.
x of axis of symmetry:
x
=
−
b
2
a
=
3
-> b = -6a
Writing that the graph passing at point (1, 0) and point (4, -3):
(1) 0 = a + b + c -> c = - a - b = - a + 6a = 5a
(2) -3 = 16a + 4b + c --> -3 = 16a - 24a + 5a = -3a --> a = 1
b = -6a = -6; and c = 5a = 5
y
=
x
2
−
6
x
+
5
Check with x = 1: -> y = 1 - 6 + 5 = 0. OK
Sum = n/2[2a + (n - 1)d] where a = first term, n = number of terms and d = common difference
(a) 30/2(2 x 5 + (30 - 1) x d) = 1455
10 + 29d = 1455 / 15
29d = 97 - 10
d = 87 / 29 = 3
(b) 7/2(2 x 9 + (7 - 1)d) = 0
18 + 6d = 0
6d = -18
d = -3
Answer:
The length of the longer ladder is 35 ft Step-by-step explanation: Please check the attachment for a diagrammatic representation of the problem We want to calculate the length of the longer ladder ; We make reference to the diagram Since the two right triangles formed are similar. the ratios of their sides are equal; Thus; 20/15 = 28/x + 15 20(x + 15) = 15(28) 20x + 300 = 420 20x = 420-300 20x = 120 x = 120/20 x = 6 So we want to calculate the hypotenuse of a right triangle with other sides 28ft and 21 ft To do this, we use the Pythagoras’ theorem which states that square of the hypotenuse equals the sum of the squares of the two other sides Let the hypotenuse be marked x x^2 = 28^2 + 21^2 x^2 = 1,225
x = √1225
x = 35 ft
Answer:
$30.
Step-by-step explanation:
70/28 = 2.5
12 x 2.5 = 30
