Đáp án:
a) x= 50
b) x = 12
Giải thích các bước giải:
a)(29-x)/(21) + (27-x)/(23) + (25-x)/(25) + (23-x)/(27) + (21-x)/(29) = -5
-> (29-x)/(21) + 1 + (27-x)/(23) + 1 + (25-x)/(25) + 1 + (23-x)/(27) + 1 + (21-x)/(29) + 1 = -5 + 5
-> (29 - x + 21)/(21) + (27 - x + 23)/(23) + (25 - x + 25)/25 + (23 - x + 27)/(27) + (21 - x + 29)/(29) = 0
-> (50 - x)/(21) + (50 - x)/(23) + (50 - x)/(25) + (50 - x)/(27) + (50 - x)/(29) = 0
-> (50 - x)(1/21 + 1/23 + 1/25 + 1/27 + 1/29) = 0
mà 1/21 + 1/23 + 1/25 + 1/27 + 1/29 > 0
-> 50 - x = 0
-> x = 50
b)
-> (4.4^5 / 3.3^5) . (6.6^5 / 2.2^5) = 2^x
-> (4.4^5 / 2.2^5) . (6.6^5 / 3.3^5) = 2^x
-> [2. (4/2)^5 ] . [2. (6/3)^5] = 2^x
-> 2^2. 2^5 . 2^5 = 2^x
-> 2^12 = 2^x
-> x = 12
