Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a.
\(\left[3\times\left(-2\right)-\left(-8\right)\right]\times\left(-7\right)-\left(-2\right)\times\left(-5\right)=\left(-6+8\right)\times\left(-7\right)-10=2\times\left(-7\right)-10=-14-10=-24\)
b.
\(85\times\left(35-27\right)-35\times\left(85-27\right)=85\times35-85\times27-35\times85+35\times27=\left(85\times35-35\times85\right)-27\times\left(85-35\right)=-27\times50=-1350\)
c.
\(\left(20\times2^4-12\times2^3-48\times2^2\right)^2\div\left(-8\right)^2=\left(\frac{5\times4\times2^4-3\times4\times2^3-3\times16\times2^2}{-8}\right)^2=\left(\frac{5\times2^2\times2^4-3\times2^2\times2^3-3\times2^4\times2^2}{\left(-2\right)^3}\right)^2\)\(=\left(\frac{2^5\times\left(5\times2-3-3\times2\right)}{-\left(2^3\right)}\right)^2=\left(-2^2\right)^2=16\)
a) \(D=\frac{1}{7}+\frac{1}{7^2}+\frac{1}{7^3}+...+\frac{1}{7^{100}}\)
\(\Rightarrow7D=1+\frac{1}{7}+\frac{1}{7^2}+...+\frac{1}{7^{99}}\)
\(\Rightarrow7D-D=\left(1+\frac{1}{7}+\frac{1}{7^2}+...+\frac{1}{7^{99}}\right)-\left(\frac{1}{7}+\frac{1}{7^2}+\frac{1}{7^3}+...+\frac{1}{7^{100}}\right)\)
\(\Rightarrow6D=1-\frac{1}{7^{100}}\)
\(\Rightarrow D=\left(1-\frac{1}{7^{100}}\right).\frac{1}{6}\)
a)(357.252.714):510=(57.77.54.714):510=(511.721):510=5.721
b)=215.520.212.54 /22.52=227.524/22.52=225.522
Mời bạn tham khảo các link sau:
a),b),c):https://hoidap247.com/cau-hoi/214111
d):https://olm.vn/hoi-dap/detail/78449788871.html
bài giải
A)2^3-5^3:5^2+12.2^2=51
B)5[(85-35:7):8+90]-50=450
C)[(7-3^3:3^2):2^2+99]-100=0
D)2^7:2^2+5^4:5^3.2^4-3.2^5=16
a) 23 – 53 : 52 + 12 . 22
= 23 - 5 + 22 . 3 . 22
= 23 - 5 + 48
= 8 - 5 + 48
= 51
b) 5 [ ( 85 – 35 : 7) : 8 + 90 ] – 50
= 5 [ ( 85 - 5 ) : 8 + 90 ] - 50
= 5 [ 80 : 8 + 90 ] - 50
= 5 [ 10 + 90 ] - 50
= 5 . 100 - 50
= 500 - 50
= 450
c) [ ( 7 – 33 : 32 ) : 22 + 99 ] – 100
= [ ( 7 - 3 ) : 22 + 99 ] - 100
= [ 22 : 22 + 99 ] - 100
= [ 1 + 99 ] - 100
= 100 - 100
= 0
d) 27 : 22 + 54 : 53. 24 – 3.25
= 25 + 5 . 24 - 3 . 25
= 25 ( 1 - 3 ) + 5 . 24
= 25 . ( - 2 ) + 5 . 24
= 16
Mỏi tay . Hok tốt nhé