So sánh 
​a ) 715và1021" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">715và1021
b ) \(\frac{-3}{200}\text{và}\frac{1}{9999}\)

c)2137và199188" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">2137và199188

d)−3457và−343434575757" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">−3457và−343434575757

e)35và−165" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">−335và−165
g) −1959và2009−2008" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">−1959và2009−2008
h)−34" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">0,75và−34
i ) 54và20092008" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">54và20092008

Tính số đo góc A của tam giác ABC biết rằng: A^=19B^=3C^" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-family:helvetica neue,helvetica,arial,sans-serif; font-size:14px; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-wrap:normal" class="MathJax">23A^=19B^=3C^$23\hat{A}=19\hat{B}=3\hat{C}$ (Làm tròn đến phút)

Cho tam giác ABC, biết ACB^=30∘." role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">ACBˆ=30∘.$\widehat{ACB}={30}^{\circ }.$ Vẽ cung tròn tâm A bán kính bằng BC, vẽ cung tròn tâm C bán kính bằng BA chúng cắt nhau ở D. (D và B nằm khác phía đối với AC.) Tính CAD^" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">CADˆ$\widehat{CAD}$ ?

Tính giá trị biểu thức bằng cách hợp lý nhất:

P=23−(−14)+35−745−(−59)+12+135

Tìm số có 4 chữ số abcdbiết số đó chia hết cho 3 và a:b:c:d = 2:1:2:3

Viết các số sau dưới dạng phân số −ab với a, b thuộc Z, b khác 0 để chỉ ra rằng các số đó là số hữu tỉ: 0; 2; 5; 21; 3; -3.

Chứng minh rằng:

n+1−2n+1+" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">3 n+1−2n+1+$3^{n+1}-2^{n+1}+$ n−1−2n−1" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">3n−1−2n−1$3^{n-1}-2^{n-1}$ chia hết cho 10 với mọi số tự nhiên n >1

1) Độ dài cạnh góc vuông của một tam giác vuông cân ABC tại A có đường phân giác kẻ từ đỉnh A bằng \(\frac{3\sqrt{2}}{2}\)32√2 là:
A.4
B.2
C.3

Cho ab=cd(b+d≠0)" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">ab=cd(b+d≠0)${\displaystyle \frac{a}{b}}={\displaystyle \frac{c}{d}}\left(b+d\ne 0\right)$ . Chứng minh: 4a2+4c24b2+4d2=(a−c)2(b−d)2" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; font-size:18px; font-style:normal; font-weight:normal; letter-spacing:normal; line-height:normal; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; padding:0px; position:relative; text-align:left; text-indent:0px; text-transform:none; white-space:nowrap; word-spacing:normal; word-wrap:normal" class="MathJax">4a2+4c24b2+4d2=(a−c)2(b−d)2