Hỏi đáp về Ôn tập chương III - Hình học 12

Có thể tìm được hai chữ số a và b sao cho phân số \(\dfrac{a}{b}\) bằng số thập phân a,b hay không ?

Tìm số tự nhiên có hai chữ số sao cho tỉ số đó với tổng các chữ số của nó là lớn nhất ?

Có bao nhiêu cách viết phân số \(\dfrac{1}{5}\) dưới dạng tổng của hai phân số \(\dfrac{1}{a}+\dfrac{1}{b}\) với \(0< a< b\) ?

Chứng minh rằng :

                \(S=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{20}}< 1\)

Tính giá trị biểu thức :

        \(P=\dfrac{2.3.4-2.3.4.9+2.3.4.11+2.3.4.13}{5.6.7-5.6.7.9+5.6.7.11-5.6.7.13}\)

Phân số \(\dfrac{a}{b}\) sau khi rút gọn được phân số \(\dfrac{-8}{11}\). Biết \(b-a=190\), tìm phân số \(\dfrac{a}{b}\) ?

Chứng minh rằng :               

               \(S=\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{2}\)

Tìm \(x\), biết :

              \(\left(\dfrac{1}{12}+3\dfrac{1}{6}-30,75\right)x-8=\left(\dfrac{3}{5}+0,415+\dfrac{1}{200}\right):0,01\)

Tính :

                    \(1\dfrac{13}{15}.0,75-\left(\dfrac{104}{195}+25\%\right).\dfrac{24}{47}-3\dfrac{12}{13}:3\)

Tìm số nguyên \(x\), biết rằng :

                \(4\dfrac{1}{3}.\left(\dfrac{1}{6}-\dfrac{1}{2}\right)\le x\le\dfrac{2}{3}.\left(\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{3}{4}\right)\)

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tính

B = \(\dfrac{1}{18}+\dfrac{1}{54}+\dfrac{1}{108}+...+\dfrac{1}{990}\)

tìm x biết:................

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5\(\dfrac{8}{17}\): x + (-\(\dfrac{1}{17}\)) : x + 3\(\dfrac{1}{17}\): 17\(\dfrac{1}{3}\)= \(\dfrac{4}{17}\)

\(\dfrac{1}{1.4}\)+ \(\dfrac{1}{4.7}\)+ \(\dfrac{1}{7.10}\)+ ... + \(\dfrac{1}{x.\left(x+3\right)}\)= \(\dfrac{6}{19}\)

So sánh hai biểu thức A và B, biết rằng:

A = \(\dfrac{2012}{2013}\)+ \(\dfrac{2013}{2014}\) và B =\(\dfrac{2012+2013}{2013+2014}\).

so sánh 2 phân số,giúp mk với

:A=\(\dfrac{2005^{2005}+1}{2005^{2006}+1};B=\dfrac{2005^{2004}+1}{2005^{2005}+1}\)

1\(\dfrac{3}{5}\) + 0,25 x \(\dfrac{16}{15}\)- \(\dfrac{13}{15}\)

X+7/3x=2/3

Chứng minh rằng nếu 3 số lập thành một cấp số nhân, đồng thời lập thành cấp số cộng thì ba số ấy bằng nhau ?

Ba số có tổng là 217 có thể coi là các số hạng liên tiếp của một cấp số nhân, hoặc là các số hạng thứ hai, thứ 9 và thứ 44 của một cấp số cộng. Hỏi phải lấy bao nhiêu số hạng đầu của cấp số cộng để tổng của chúng là 820 ?

bạn Nga đọc đc 1 cuốn sách trong 3 ngày. Ngày đầu bạn đọc đc 20% số trang sách. Ngày 2 đọc đc \(\dfrac{2}{3}\) số trang sách còn lại. Ngày 3 đọc nốt 200 trang. Hỏi cuốn sách dài bao nhiêu trang ?

trong mặt phẳng oxyz cho tứ diện ABCD có A(2;3;1),B(4;1;-20,c(6;3;7),D(-5;-4;-8).độ dài đường cao kẻ từ d cảu tứ diện là

Tính diện tích hình vuông nội tiếp hình tròn . Biết diện tích hình tròn bằng 12cm2