Ineed explain how to do these two question as i did the rest of them. i just don't understand these.

7. (4x +10)/(x^3 +3x^2 -16x -48)

9. -320/93

Step-by-step explanation:

7. As with adding any fractions, first you find a common denominator. When the fractions are rational expressions, it often helps to factor the denominators.

6/(x^2 -16) -2/(x^2 -x -12) = 6/((x -4)(x +4)) -2/((x -4)(x +3))

= (6(x +3) -2(x +4))/((x -4)(x +3)(x +4)) . . . . . using a common denominator

= (6x +18 -2x -8)/((x -4)(x +3)(x +4))

= (4x +10)/((x^2 -16)(x +3))

= (4x +10)/(x^3 +3x^2 -16x -48)

9. First you simplify the denominator:

2/25 -5/16 = (2·16 -5·25)/(25·16) = -93/400

Then you perform the division. This can be done by multiplying by the inverse of the denominator.

(4/5)/(2/5 -5/16) = (4/5)·(-400/93) = -320/93

b

step-by-step explanation:

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.