A= 7/38.9/11+7/38.4/11-7/38.2/11
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Ta có A = 710 + 79 - 78
= 78( 72 + 7 - 1 )
= 78 . 55 ⋮ 11 vì 55 ⋮ 11
Vậy A ⋮ 11
b) Ta có B = 115 + 114 + 113
= 113( 112 + 11 + 1 )
= 113 . 133 ⋮ 7
Vậy B ⋮ 7
a,A=710+79-78=78(72+7-1)=78x55 ⋮11 vì 55⋮11
b,115+114+113=113(112+11+1)=113x133⋮7 vì 133⋮7
![](https://rs.olm.vn/images/avt/0.png?1311)
Dạng tổng quát của 1 STn a cho 11 dư 7 là:
a/ a=11k + 7 chọn í a nhé!
b/ a:11 = k +7
c/a- 11^k+7
d/ a=11 (k+7)
![](https://rs.olm.vn/images/avt/0.png?1311)
a
\(\dfrac{121.75.130.169}{39.60.11.198}\\ =\dfrac{11.11.5.5.3.13.2.5.13.13}{13.3.2.2.3.5.11.18.11}\\ =\dfrac{5.13.5.13}{2.3.18}\\ =\dfrac{65.65}{108}\\ =\)
tự tính
\(b\\ \dfrac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}.9.5^{11}.7^{11}}\\ =\dfrac{5^{11}.7^{11}.2.7}{5^{12}.7^{11}.7.9.5^{11}.7^{11}}\\ =\dfrac{2}{5^{12}.7^{11}.9.}\\ =\)\
tự tính nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
\(E=\left(-\dfrac{3}{7}+\dfrac{4}{11}\right):\dfrac{7}{11}+\left(-\dfrac{4}{7}+\dfrac{7}{11}\right):\dfrac{7}{11}\)
\(=\left(-\dfrac{3}{7}+\dfrac{4}{11}\right).\dfrac{11}{7}+\left(-\dfrac{4}{7}+\dfrac{7}{11}\right).\dfrac{11}{7}\)
\(=\dfrac{11}{7}\left[\left(-\dfrac{3}{7}\right)+\dfrac{4}{11}+\left(-\dfrac{4}{7}\right)+\dfrac{7}{11}\right]\)
\(=\dfrac{11}{7}\left[\left(-\dfrac{3}{7}+\dfrac{-4}{7}\right)+\left(\dfrac{4}{11}+\dfrac{7}{11}\right)\right]\)
\(=\dfrac{11}{7}\left[\left(-1\right)+1\right]\)
\(=\dfrac{11}{7}.0=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: 10+8=18 chia hết cho 9
b: 1531 chia 2 dư 1
2001 chia 2 dư 1
=>1531+2001 chia 2 dư 2
=>1531+2001 chia hết cho 2
c: (10+5)=15 chia hết cho 3
10+5=15 ko chia hết cho 9
d:Sửa đề: 11+11^2+11^3+11^4+11^5+11^6
=11(1+11)+11^3(1+11)+11^5(1+11)
=12(11+11^3+11^5) chia hết cho 12
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
\(\begin{array}{l}{11^7}{.11^3} =11^{7-3}={11^4};\,\,\,\,\,\,\,{11^7}:{11^7} =11^{7-7}=11^0= 1;\\{7^2}{.7^4} = 7^{2+4}= {7^6};\,\,\,\,\,\,\,\,\,\,\,\,\,{7^2}{.7^4}:{7^3} = 7^{2+4-3}= {7^3}.\end{array}\)
b) +) Phép tính đúng là:
\({9^7}:{9^2} = {9^5}\) vì \({9^7}:{9^2}=9^{7-2} = {9^5}\)
+) Các phép tính sai là:
\({2^{11}}:{2^8} = 6 \) vì \({2^{11}}:{2^8} = 2^{11-8} = 2^3\) ;
\({7^{10}}:{7^2} = {7^5}\) vì \({7^{10}}:{7^2} = 7^{10-2} = 7^8\);
\({5^6}:{5^6} = 5\) vì \({5^6}:{5^6}=5^{6-6}=5^0 =1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\dfrac{7}{38}\left(\dfrac{9}{11}+\dfrac{4}{11}-\dfrac{2}{11}\right)=\dfrac{7}{38}\cdot1=\dfrac{7}{38}\)