simplify help me??

Question

(9) / (5a^2) - (2)/(a)=

Answer 1

take lcm
(9-10a)/5a^2
this is how far it can be done

Answer 2

9/(5a^2) - 2/a
Multiply both numerator and denominator of the second term by 5a so that the denominators of both terms are equal.

9/5a^2-10a/5a^2=(9-10)/5a^2 = -1/5a^2

You can't add or subtract two fractions unless the denominators are the same. So you must do what it takes to make them the same. Example; Add 1/2+1/3.

We must change 1/2 to its equa 3/6 and 1/3 to its equal 2/6. Now that the denominators are the same we just add the numerators and put the sum over the common denominator.
This gives (2+3)/6 = 5/6

Answer 3

= (9)/(5a^2) - ((5a)/(5a))*(2)/(a)
= (9)/(5a^2) - (5a)*(2)/((a)*(5a))
= (9)/(5a^2) - (10a)/(5a^2)
= (9-10*a)/(5a^2)

I agree with you, the answer is not really simpler, but I think your teacher meant to ask to put the expression over a common denominator. Teachers are like that some times, you have to guess what they want from the pattern of previous questions.

Answer 4

9 / (5a^2) - 2 / a =
9 / (5a^2) - (2 * 5a) / (a * 5a) =
9 / (5a^2) - 10a / (5a^2) =
(9 - 10a) / (5a^2)

Answer 5

(9) / (5a^2) - (2)/(a)
=(9*a) - 2*(5a^2) / (5a^2)*(a)
=(9a - 10a^2) / (5a^2)*(a)
=(9a - 10a^2) / 5a^3
=a*(9 - 10a) / 5a^3
=(9 - 10a) / 5a^2