145 = -16 t² + 80 t +s
s = ?
v = v0 - at
0 = 80 - at
80 = at
s = 80 t - at²/2
s = 80 t - 80t/2
s = 40 t
Finally: 145 = -16 t² + 80 t + 40 t
16 t² - 120 t + 145 = 0
We will solve this quadratic equation:
t = [120 +√ ( (-120)²- 4 · 16 · 145 )] / 32
t = [120 + √ (14400 - 9280) ] / 32
t = (120 + 71.55) / 32 = 5.98 ≈ 6 s
Answer:D) 6 seconds
Answer:
4 : 7
Step-by-step explanation:
No. of families = 2400
No. of cars = 4200
Family : Cars
= 2400 : 4200
= 24 : 42
= 6 x 4 : 6 x 7
= 4 : 7
9x - 4 = -44
•add 4 to both sides to isolate the variable
9x = -40
•divide both sides by 9 to isolate the variable
x = -40/9 or −4.444...
The steps are to first distribute the 1/3 into (x-9) and then to move the +6 on the left over to the right:
First distribute:
y + 6 = 1/3(x-9) becomes y + 6 = 1/3x-3
Now subtract 6 from both sides:
y = 1/3 x - 3 - 6
y = 1/3 x - 9
