Câu 1:Bỏ dấu ngoặc rồi thu gọn biểu thức a, A=(a+b) – (a-b) + (a-c) – (a+c) b, B=(a+b-c) + ( a-b+c) – ( b+c-a) – ( a-b-c) 06/12/2021 Bởi Camila Câu 1:Bỏ dấu ngoặc rồi thu gọn biểu thức a, A=(a+b) – (a-b) + (a-c) – (a+c) b, B=(a+b-c) + ( a-b+c) – ( b+c-a) – ( a-b-c)
Đáp án: a, `A` `=` $\text{( a + b ) – ( a – b ) + ( a – c ) – ( a + c )}$ $\text{A = a + b – a + b + a – c – a – c}$ $\text{A = 2b – 2c}$ b, $\text{B = ( a + b – c ) + ( a – b + c ) – ( b + c – a ) – ( a – b – c )}$ $\text{B = a + b – c + a – b + c – b – c + a – a + b + c }$ $\text{B = 2a}$ Bình luận
@py Bài làm : a, `A = (a+b)-(a-b)+(a-c)-(a+c)` `= a + b – a + b + a – c – a – c` `=( a – a ) + ( b + b ) + ( a – a ) + ( – c – c )` `= 0 + 2b + 0 + – 2c` `= 2b – 2c` b, `B=(a+b-c)+(a-b+c)-(b+c-a)-(a-b-c)` `= a + b – c + a – b + c – b – c + a – a + b + c` `= ( a – a ) + ( b – b ) + ( c – c ) + ( b – b ) + ( c – c ) + ( a + a )` `= 0 + 0 + 0 + 0 + 0 + 2a` `= 2a` Bình luận
Đáp án:
a,
`A` `=` $\text{( a + b ) – ( a – b ) + ( a – c ) – ( a + c )}$
$\text{A = a + b – a + b + a – c – a – c}$
$\text{A = 2b – 2c}$
b,
$\text{B = ( a + b – c ) + ( a – b + c ) – ( b + c – a ) – ( a – b – c )}$
$\text{B = a + b – c + a – b + c – b – c + a – a + b + c }$
$\text{B = 2a}$
@py
Bài làm :
a, `A = (a+b)-(a-b)+(a-c)-(a+c)`
`= a + b – a + b + a – c – a – c`
`=( a – a ) + ( b + b ) + ( a – a ) + ( – c – c )`
`= 0 + 2b + 0 + – 2c`
`= 2b – 2c`
b, `B=(a+b-c)+(a-b+c)-(b+c-a)-(a-b-c)`
`= a + b – c + a – b + c – b – c + a – a + b + c`
`= ( a – a ) + ( b – b ) + ( c – c ) + ( b – b ) + ( c – c ) + ( a + a )`
`= 0 + 0 + 0 + 0 + 0 + 2a`
`= 2a`