Question

3. Evaluate
(1) 3a - (a + 2b)
pls explain why the answer is 2a - 2b​

Answer 1

Step-by-step explanation:

$3a - (a + 2b)$

here. (a+2b) means +a +2b

and multiply with (-)

(-)(+a+2b) = (-)×(+a) + (-)(+2b)

$( - ) \times ( + ) = -$

(-)×(+a) = -a.

(-)×(+2b)= -2b

Hence

$3a - (a + 2b) = 3a - a - 2b \\ \\ = 2a - 2b$

Answer 2

3a – (a + 2b)

= 3a – a – 2b

= 2a – 2b

= 2 (a – b)

Explanation

3a – (a + 2b)

[Open bracelet so ,sign change 3a - (a + 2b) became 3a - a - 2b]

= 3a – a – 2b

[(a) is subtracted from (3a) so it become 2a (3a - a = 2a)]

= 2a – 2b

[Taking 2 common]

= 2 (a – b)