4. perform the indicated operation on polynomials.
a. (4x2 + 5x - 7) + (2x2 - 7x - 3)
b. (8m - 2n - 4) - (6m - 3n + 2)
c. (30+4) (5c-2)

Step-by-step explanation:

a) (4x2 + 5x - 7) + (2x2 - 7x - 3)

This is an addition question. We have to perform addition

The first step is open the parenthesis/brackets.

4x^2+5x-7 + 2x^2 -7x-3

Arrange the terms according to the exponents:

4x^2+2x^2-7x+5x-7-3

Combine the like terms:

6x^2-2x-10

Thus the answer is 6x^2-2x-10

b)  (8m - 2n - 4) - (6m - 3n + 2)

We have to perform subtraction:

There is a rule in the subtraction that when you open the brackets then the signs of 2nd bracket will be multiplied by the negative sign:

Open the brackets:

8m - 2n - 4 - 6m+3n-2

Arrange the terms:

8m-6m+3n-2n-4-2

Combine the like terms:

2m+n-6

Thus the answer is 2m+n-6

c) (30+4) (5c-2)

This expression shows the operation of multiplication:

Solve the first parenthesis.

(34)(5c-2)

Now multiply 34 by each term of 2nd bracket:

=170c-68

Thus the answer is 170c-68

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m