When you want to write a polynomial, you should write the term with the highest degree first.
Here, it should go like this: d^3 + d^2 - d + 3
This means that the term which should be written first is the cubic term.
21 and download math papa
Let x be the length of the train.
On the basis of the observer;
Speed of the train = x/6
On the basis of the bridge;
Total distance covered by any point of the train= 350+x
Speed = (350+x)/20
Equating the two expressions of speed;
x/6 = (350+x)/20
20(x) = 6(350+x)
20x = 2100+6x
(20-6)x = 2100
14x = 2100
x= 2100/14 = 150 m
Speed = x/6 = (350+x)/20 = 150/6 = 500/20 = 25 m/s.
Therefore,
Length of train = 150 m
Speed of train = 25 m/s
The factored expression is: 3(5n-6)
The GCF between 15 and 18 is 3. So you would divide both numbers by 3. That would leave you with 5 taking the place of 15 and 6 taking the place of 18. Then you would fill in the blanks. Three multiplied by the expression 5n-6 would give you your original expression of 15n-18.