100 POINTS plz help Chuck drops a rock from a height of 70 m. How long will it take the rock to hit the ground?
2 answers:
Answer:
3.8
Step-by-step explanation:
We are going to plug in the values of the equation, so h(t)=-4.9^2+v0t+h0 will
now be h(t)=-4.9^2+0+70
Now we will find the a b and c of the equation, a=-4.9 b=0 c=70
Now we must find the discriminant of the equation, which the equation for that is D=b^2+(-4)(a)(c)
So D=1,372
Now we use the quadratic formula (see picture below for finished product)
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Answer:
a. 1 1/8 b. 8/9
Step-by-step explanation:
You can set this up as a proportion to solve. For part a. we know that 2/3 of the road is 3/4 mile long. 2/3 + 1/3 = the whole road, so we need how many miles of the road is 1/3 its length. Set up the proportion like this:
Cross multiplying gives you:
The 3's on the right cancel out nicely, leaving you with
To solve for x, multiply both sides by 3/2:
gives you
That means that the road is still missing 3/8 of a mile til it's finished. The length of the road is found by adding the 3/4 to the 3/8:
So the road is a total of 1 1/8 miles long.
For b. we need to find out how much of 1 1/8 is 1 mile:
1 mile = x * 9/8 and
x = 8/9. When 1 mile of the road is completed, that is 8/9 of the total length of the road completed.