Question

solve these 2 exercises please.
a + (a-b) + (- a + b)

a²+[-b²+2a²]-[a²-b²]

Answer 1

first remember that:
- × - = +
+ × + = +
- × + = -
+ × - = -
and:
$(- a {})^{2} = a {}^{2}$

a+ (a-b) + (-a+b)=
a + a -b -a+b= a

${a}^{2} + ( - b {}^{2} + 2a {}^{2} ) - ( {a}^{2} - {b}^{2} ) = \\ a {}^{2} + b {}^{2} + 2a {}^{2} - a {}^{2} - b {}^{2} = 2a {}^{2}$

please mark as brainliest answer.

Answer 2

First Part:
For every parenthesis with a plus sign to its left, you can eliminate the parenthesis (take into account that plus×minus=minus)

a + a - b - a + b

Then you add like terms. This means you add/subtract a with a and same with b and b (I'll organize the terms in alphabetical order but it's not neccesary)

a + a - a - b + b

Since a - a =0 and b - b = 0,

a + 0 + 0
Answer: a

Second part
Since you have a minus to the left of a parenthesis, you have to change the signs of all the terms inside the parenthesis before you eliminate the parenthesis.

$= {a}^{2} - {b}^{2} + 2 {a}^{2} - {a}^{2} + {b}^{2} \\ = {a}^{2} + 2 {a}^{2} - {a}^{2} - {b}^{2} + {b}^{2} \\ 2 {a}^{2} + 0 + 0$
Answer: 2a^2