Answer:
Step-by-step explanation:
Let +s+ = the speed of the passenger train
+s+-+20%5D+ = the speed of the freight train
Let +t+ = time in hours for both trains
-------------------------------------
Equation forpassenger train:
(1) +280+=+s%2At+
Equation for freight train:
(2) +180+=+%28+s-20+%29%2At+
------------------------
(1) +t+=+280%2Fs+
Substitute (1) into (2)
(2) +180+=+%28+s-20+%29%2A%28+280%2Fs+%29+
(2) +180s+=+280s+-+5600+
(2) +100s+=+5600+
(2) +s+=+56+
and
+s+-+20+=+36+
The speed of the passenger train is 56 mi/hr
The speed of the freight train is 36 mi/hr
-------------------------------------
check:
(1) +280+=+56%2At+
(1) +t+=+5+
and
(2) +180+=+%28+56-20+%29%2At+
(2) +180+=+36t+
(2) +t+=+5+
OK
f(-2) means replace x in the equation with -2, then solve:
-2^2 +5(-2)
Simplify:
4 + -10
Add:
-6
Answer:
r=-6
Step-by-step explanation:
Question: -3+r/3=-5
1) Multiply both sides of the equation by 3:
-9+r=-15
2) Add 9 to both sides:
r=-6
Footnotes:
1) In step 1 when I multiplied both sides of the equation by 3, don't forget you also have to multiply -3 by 3 because it is not part of the fraction (which is how I got -9)
Answer:
9/20 yes, 4/15 not. See below
Step-by-step explanation:
Pick 9/20 and multiply numerator and denominator by 5:
9/20 = 45/100
We know that if we divide a number by 100 we need to move the coma as two places left, so:
9/20 = 45/100 = 0.45
And this is a terminal decimal as we know where it ends.
On the other hand if we pick 4/15 let try to divide it (here I will do it 'manually'):
4 |_ 15
we can divide 4 by 15, so we use 40 and begin with a comma
40 |_ 15
0.
15 enters 2 times in 40 with a rest of 10, so:
40 |_ 15
30 0.2
100
100 divided by 15 is 6 and we have 10 as rest again, and again and again...
40 |_ 15
30 0.266.....
100
100
....
So, we will have 0.266666666666666 infinitely. The decimal for 4/15 is non terminating and is 0.26666666666666666...
Answer:
(-8,-3)
Step-by-step explanation:
This question is similar to the vertex form of a quadratic equation, so you can think of this equation like f(x) = (x-h)+k. Using this equation, you can determine the vertex (h,k) of |x+8|-3, which is (-8,-3).
