Question

cho (a+b)² =2.(a² +b²)  chứng minh rằng a=b

Answer 1

Ta có:

(a+b)²=2(a²+b²)

<=>a²+2ab+b²=2a²+2b²

<=>2ab=a²+b²

<=>a²-2ab+b²=0

<=>(a-b)²=0

<=>a=b(đpcm)

Answer 2

(a+b)²=2.(a²+b²)

=> a²+2ab+b²=2a²+2b²

=> -2a²+a²-2b²+b²+2ab=0

=> -a²-b²+2ab=0

=> -a²+2ab-b²=0

=> -(a²-2ab+b²)=0

=> -(a-b)²=0

=> (a-b)²=0

=> a-b=0

=> a=b

Answer 3

  (a+b)² =2.(a² +b²)  

<=>a²+2ab+b²-2a²-2b²=0

<=>-a²+2ab-b²=0

<=>-(a-b)²=0

<=>a-b=0

<=>a=b

Answer 4

Đây là ccaau trả l