toán đề cương lớp 7

N

ngocsangnam12

Cho $a, b, c$ thỏa mãn: $\frac{a}{2014}=\frac{b}{2015}=\frac{c}{2016}$
Chứng minh: $4(a-b)(b-c) = (c-a).(c-a)$
Theo có:
$\frac{a}{2014}=\frac{b}{2015}=\frac{c}{2016}=k$
=> a=2014k ; b= 2015k ; c=2016k
Theo đề ra:
$4(a-b)(b-c)=4.(2014k-2015k)(2015k-2016k)=4.(-1k)(-1k)=4.k^2=(2k)^2$
$= (2016k-2014k)^2=(c-a)^2=(c-a).(c-a)$

 
You must log in or register to reply here.
Top Bottom