Answer:
a
Step-by-step explanation:
Given
3(x + 3)² - 81 = 0 ( add 81 to both sides )
3(x + 3)² = 81 ( divide both sides by 3 )
(x + 3)² = 27 ( take the square root of both sides )
x + 3 = ± = ± 3
( subtract 3 from both sides )
x = - 3 ± 3
x = - 3 - 3 or x = - 3 + 3
→ a
The <em>speed</em> intervals such that the mileage of the vehicle described is 20 miles per gallon or less are: v ∈ [10 mi/h, 20 mi/h] ∪ [50 mi/h, 75 mi/h]
<h3>How to determine the range of speed associate to desired gas mileages</h3>In this question we have a <em>quadratic</em> function of the <em>gas</em> mileage (g), in miles per gallon, in terms of the <em>vehicle</em> speed (v), in miles per hour. Based on the information given in the statement we must solve for v the following <em>quadratic</em> function:
g = 10 + 0.7 · v - 0.01 · v² (1)
An effective approach consists in using a <em>graphing</em> tool, in which a <em>horizontal</em> line (g = 20) is applied on the <em>maximum desired</em> mileage such that we can determine the <em>speed</em> intervals. The <em>speed</em> intervals such that the mileage of the vehicle is 20 miles per gallon or less are: v ∈ [10 mi/h, 20 mi/h] ∪ [50 mi/h, 75 mi/h].
To learn more on quadratic functions: brainly.com/question/5975436
#SPJ1
