Câu hỏi của Hari Won

Question

tìm x biết : 1+ 3+ 5+ .....+ x =1600 ( x là số tự nhiên lẻ )

Sếp Việt Đẹp Trai · Accepted Answer

$\text{1+ 3+ 5+ .....+ x =1600 }$$\left\{\frac{\left(n-1\right)}{2+1}\right\}^2=1600$$\left\{\frac{\left(n-1\right)}{2+1}\right\}^2=40^2$$\left\{\frac{\left(n-1\right)}{2+1}\right\}=40$$\left\{\frac{\left(n-1\right)}{2}\right\}=40-1$$\left\{\frac{\left(n-1\right)}{2}\right\}=39$$n-1=39.2$$n-1=78$$n=78+1$$n=79$Câu trả lời: $\text{1+ 3+ 5+ .....+ x =1600 }$$\left\{\frac{\left(n-1\right)}{2+1}\right\}^2=1600$$\left\{\frac{\left(n-1\right)}{2+1}\right\}^2=40^2$$\left\{\frac{\left(n-1\right)}{2+1}\right\}=40$$\left\{\frac{\left(n-1\right)}{2}\right\}=40-1$$\left\{\frac{\left(n-1\right)}{2}\right\}=39$$n-1=39.2$$n-1=78$$n=78+1$$n=79$

Khoá học trên OLM (olm.vn)

Khoá học trên OLM (olm.vn)