Answer:
A.
Step-by-step explanation:
so, the equation is
h(t) = -t² + 7t
so, we need to find the solutions for t (the time when the ball is exactly 10 ft in the air). there had to be 2 solutions, as the ball first goes up passing the 10 ft height, and then comes back down again, passing the 10 ft mark a second time. and between these 2 times the ball is higher (but not equal, so, we can only use < or > as inequality signs) than 10 ft.
10 = -t² + 7t
-t² + 7t - 10 = 0
the generation solution to a quadratic equation is
x = (-b ± sqrt(b² - 4ac))/(2a)
in our case
x = t
a = -1
b = 7
c = -10
t = (-7 ± sqrt(7² - 4×-1×-10))/(2×-1) =
= (-7 ± sqrt(49 - 40))/-2 = (-7 ± sqrt(9))/-2
t1 = (-7 + 3)/-2 = -4/-2 = 2 seconds
t2 = (-7 - 3)/-2 = -10/-2 = 5 seconds
so, between 2 and 5 seconds airtime the ball is higher than 10 ft.
and remember : HIGHER THAN.
so, we cannot use any equality (like <= or >=).
t must be higher than 2 and lower than 5 :
2 < t < 5
Answer:
c
Step-by-step explanation:
im DORA
Answer:
44 hours
Step-by-step explanation:
Topic of this question: Creating and Solving Equations, Rates, and Proportions
<h2>
Method 1: Creating and Solving Equations</h2>
Step 1: Find the amount drilled per hour
To do this, we have to divide the amount drilled by the number of hours it took to drill and find how much is being drilled per hour.
(I know it's a mouthful)
-72ft = 24x, where x is the amount drilled per hour
-72ft ÷ 24 = x
-3ft = x
-3ft per hour
Step 2: Find how many hours it takes to drill to -132 ft
Since we know the rate of drilling per hour, we can divide the target amount by the amount drilled per hour
-132 ÷ -3 = y, where y is the number of hours it takes
44 = y
y = 44
It will take a total of 44 hours to drill to -132 ft
<h2>Method 2: Proportions</h2>
We can set up a proportion like this, where we know that it takes 24 hours to drill 72 ft, but we don't know how long it takes to drill 132 feet
Cross multiply
Simplify
Divide both sides by -72
It will take a total of 44 hours to dig to -132 ft
-Chetan K
Step-by-step explanation:
let's look at the last line :
x³ + 8x - 3 = Ax³ +5Ax + Bx² + 5B + Cx + D
since we find A, B, C, and D by simply comparing the factors of the various terms in x (or constants) in both sides of the equation, we need to combine a few terms on the right hand side (so that we have one term per x exponent grade).
x³ + 8x - 3 = Ax³ + (5A + C)x + Bx² + (5B + D)
by comparing now both sides, to make both sides truly equal, the factors have to be equal.
A = 1 (the same as for x³ on the left hand side).
B = 0 (a we have no x² on the left side).
5A + C = 8 (a 8 is the factor of x in the left side).
5×1 + C = 8
5 + C = 8
C = 3
5B + D = -3 (as the constant term is -3 on the left side).
5×0 + D = -3
D = -3
so, the 4th answer option is correct.
