Which of the following correctly shows the first step when factoring 5a^2b-5a^2c-5db+5dc by grouping?
1) 5a^2 (b-c)-5d(b-c)
2) 5a^2 (b+c) +5d(b+c)
3) 5a^2 (b+c) -5d(b+c)
4)5a^2 (b-c) +5d(b-c)

Correct choice is 1) .

Step-by-step explanation:

Given expression is :

Now we need to factor it by completing square to match the correct choice.

Make two groups having first two terms and last two terms then find GCF of each.

Hence correct choice is 1) .

-2/