Lesson 1: calculated by convenience
36+25-36+25
36/(1*3*5) + 36/(3*5*7) + 36/(5*7*9) + ... + 36/(25*27*29)
-[-(36)+25-(-90]-[-36-25]
Trả lời :
- [ - ( 36 ) + 25 - ( -90 )] - [ -36 - 25 ]
=36 - 25 - 90 + 36 + 25
= 90
hok tốt!
-[-(36)+25-(-90]-[-36-25]=-140
# hok tốt #
Ta có : - [ -(36) + 25 - (-90)] - [ (-36) -25 ]
= -[ (-36) + 25 + 90 ] - ( -61)
= -[ (-11) + 90 ] - ( - 61)
= ( - 79) - ( -61)
=-18
so sánh 36^25 và 25 ^36 ?
So sánh 25^36 và 36^25
CTR:36/1*3*5+36/3*5*7+36/5*7*9+...+36/25*27*29<3
\(t\text{ìm}x\left(\frac{36}{1\cdot3\cdot5}+\frac{36}{3\cdot5\cdot7}+.....+\frac{36}{25\cdot27\cdot29}\right)\cdot x=\frac{4}{25}\)
\(36.\left(\frac{1}{1}-\frac{1}{3}-\frac{1}{5}+\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+...+\frac{1}{25}-\frac{1}{27}-\frac{1}{29}\right).x=\frac{4}{25}\)
Triệt tiêu còn
\(36.\left(\frac{1}{1}-\frac{1}{29}\right).x=\frac{4}{25}\)
từ đây dễ rồi, tình lần lượt rồi tìm x nhé
so sánh : 36 mũ 25 và 25 mũ mũ 36
1. Tính hợp lý (nếu có thể)
a. (-7).(-3).17.(-1)2
b.-25.(75-45)-75.(45-25)
c. 75.(-36)+36.(-25)
d. 24.12+57.2.6+4.19.3
a. (-7).(-3).17.(-1)2
= (-7).(-3).17.1
= 21.17.1
=357.1
=357
a) \(\dfrac{2}{5}\sqrt{25}\) -\(\dfrac{1}{2}\sqrt{4}\) b)0,5\(\sqrt{0,09}\) +5\(\sqrt{0,81}\) c)\(\dfrac{2}{5}\sqrt{\dfrac{25}{36}}\) -\(\dfrac{5}{2}\sqrt{\dfrac{4}{25}}\)
d)-2\(\sqrt{\dfrac{-36}{-16}}\) + 5\(\sqrt{\dfrac{-81}{-25}}\)
`#3107.101107`
a)
`2/5 \sqrt{25} - 1/2 \sqrt{4}`
`= 2/5 * \sqrt{5^2} - 1/2 * \sqrt{2^2}`
`= 2/5*5 - 1/2*2`
`= 2 - 1`
`= 1`
b)
`0,5*\sqrt{0,09} + 5*\sqrt{0,81}`
`= 0,5*\sqrt{(0,3)^2} + 5*\sqrt{(0,9)^2}`
`= 0,5*0,3 + 5*0,9`
`= 0,15 + 4,5`
`= 4,65`
c)
`2/5\sqrt{25/36} - 5/2\sqrt{4/25}`
`= 2/5*\sqrt{(5^2)/(6^2)} - 5/2*\sqrt{(2^2)/(5^2)}`
`= 2/5*5/6 - 5/2*2/5`
`= 1/3 - 1`
`= -2/3`
d)
`-2 \sqrt{(-36)/(-16)} + 5 \sqrt{(-81)/(-25)}`
`= -2*\sqrt{36/16} + 5*\sqrt{81/25}`
`= -2*\sqrt{(6^2)/(4^2)} + 5*\sqrt{(9^2)/(5^2)}`
`= -2*6/4 + 5*9/5`
`= -3 + 9`
`= 6`