Answer:
0.448 seconds
Step-by-step explanation:
d = -16t² -4t + 412
find t when d = 407
substituting d = 407 into the equation:
407 = -16t² -4t + 412 (subtract 407 from both sides)
-16t² -4t + 412 - 407 = 0
-16t² -4t + 5 = 0 (multiply both sides by -1)
16t² + 4t - 5 = 0
solving using your method of choice (i.e completing the square or using the quadratic equation), you will end up with
t = (-1/8) (1 + √21)= -0.70 seconds (not possible because time cannot be negative)
or
t = (-1/8) (1 -√21) = 0.448 seconds (answer)
The answer is 4 3/8 boxes because 1 3/4 x 2 1/2 ＝ 4 3/8.
Answer:
Step-by-step explanation:
Add 
to both sides:
Subtract 2 from both sides:
Divide both side by 2:
Average speed is the distance traveled by an object in total and divided by the amount of time an object covers the distance. The formula is -
Average speed = total distance traveled / total time taken
= 68km+64km / 2 hrs.+3hrs.
= 132km / 5hrs.
= 26.4km/hr.
Therefore, the train's average speed is 26.4km/hr.
Step-by-step explanation:
In triangle ADE:
sum of all angles is 180.
3x-10+58+42=180
3x+90=180
3x=180-90
3x=90
x=90/3
x=30
As line DA and CB are parallel:
angle D=angle C
angle y=58
In angle BCE, sum of angles is 180.
z+58+42=180
z+100=180
z=180-100
z=80
