tinh nhanh.234 x 7 - (1347 - 579)

Bài 1 : Tính giá trị biểu thức sau :

A= ( 1/7 + 1/23 - 1/1009 ) : ( 1/23 + 1/7 - 1/1009 + 1/7 . 1/23 . 1/1009 ) + 1 : ( 30 . 1009 - 160 )

Bài 2 : Tìm số tự nhiên x biết :

a) ( 1/1.2.3 + 1/2.3.4 + .... + 1/8.9.10 )    b) 5^x = 125    c) 3^2x = 81    d) 5^2x-3 - 2.5^2 = 5^2 .3

A=1/7+1/23-1/1009/(1/23+1/7-1/1009+1/7*1/23/1/1009)+1/(30/1006-160) tinh gia tri bieu thuc

tinh gia tri bieu thuc sau:

(1/7+1/23-1/1009):(1/23+1/7-1/1009+1/7.1/23.1/1009)+1:(30.1009-160)

Tính nhanh A= (1/7 + 1/23 - 1/1009) : ( 1/23 + 1/7 - 1/1009 + 1/7. 1/23.1/1009) +1: (30.1009-160)

tinh nhanh:

(45+24-55+76)x(1/5+7/8+7/3+5/7+8/7)

tinh

\(A=\left(\frac{1}{7}+\frac{1}{23}-\frac{1}{1009}\right):\left(\frac{1}{23}+\frac{1}{7}-\frac{1}{1009}+\frac{1}{7}.\frac{1}{23}.\frac{1}{1009}\right)+1:\left(30.1009-160\right)\)

tinh

A=(\(\frac{1}{7}+\frac{1}{23}-\frac{1}{1009}\)):(\(\frac{1}{23}+\frac{1}{7}-\frac{1}{1009}+\frac{1}{7}\cdot\frac{1}{23}\cdot\frac{1}{1009}\))+1:(30.1009-160)

1+3+5+7+9+...........................1009