Solve the quadratic equation by completing the square. 3x2 - 6x - 4 = 0
1 answer:
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Answer: The second choice is answer.
Step-by-step explanation:
<h3>The first line (Blue One)</h3> (Slope is -1 and intercepts y at -3)
(Slope is 2, to find y-intercept. Substitute x = 0 then we get -8) (For x-intercept, it's 4. Just substitute y=0 to get x-intercept.)
Because there are choices, it's easy to notice.
The first one, x = -4 and almost -5 which is not right. (x is around 1 almost 2.)
The second one, x = 1 and almost 2 is right.
The third one, x = -1 and almost -2 is not right (The intersection isn't even at -1 or any negative number for x-axis.)
The fourth one, just like the first one... x = 4 almost 5
<h3>Or solve the equations.</h3>Substitute y=2x-8 in y=-x-3
Look at the value of x then find the answer that matches the value of x.
Now for y, substitute x = 5/3 in y = -x-3 (or in 2x-8 if you want.)
So the answer is the second choice.
Let's say that the speed of the freight train is and the one of the passenger train is
.
MPH means every hour the freight train covers
miles., which means in 3h it will have covered 3 times as much:
mi.
Following the same logic, MPH means every hour the passenger train covers
miles, meaning after 3h it will have covered 3 times as much as well:
mi.
Now, having expressed those distances and speeds algebraically, we find the difference between the two distances covered after 3h, knowing it will be equal to 240:
Knowing this, we can surely affirm that the freight train is travelling at 40MPH and the passenger train is travelling three times as fast, 120MPH.