Bài 2: a) 47.76 + 76.54 – 76 = 76. (47 + 54 -1) = 76. 100 = 7600 b) {[260 – (36 -31)^3 . 2] -9} . 2017 = {[260 – 5^3 .2 ]-9 }.2017 = {[260 – 125.2] -9}.2017 ={[260 – 250] -9}.2017 = {10-9}.2017 = 1.2017 = 2017 c) 11. 2^3 + 3^3. 2 – 29 = 11. 8 + 27.2 -29 = 88 + 54 – 29 = 113 Bài 3: a) 491 – (x+83) = 336 x+83 = 491 – 336 x+83 = 155 x = 155 – 83 x = 72 b) (x^2 -18) : 63 = 1 x^2 -18 = 1. 63 = 63 x^2 = 63+18 =81 Mà 9^2 = 81 => x = 9 c) 5^x+1 +5^x = 150 5^x. 5 + 5^x = 150 5^x . (5+1) = 150 5^x .6 = 150 5^x =150 : 6= 25 Mà 5^2 = 25 => x = 5 Reply
Bài 2: a. `47 . 76 + 76 . 54 – 76` `= 76 . (47 + 54 – 1)` `= 76 . 100 = 7600` b. `{[260 – (36 – 31)^3 . 2] – 9} . 2017` `= {[260 – 5^3 . 2] – 9} . 2017` `= {[260 – 250] – 9} . 2017` `= {10 – 9} . 2017` `= 1 . 2017 = 2017` c. `11 . 2^3 + 3^3 . 2 – 29` `= 11 . 8 + 27 . 2 – 29` `= 88 + 54 – 29` `= 142 – 29 = 114` Bài 3: a. `491 – (x + 83) = 336` `=> x + 83 = 491 – 336` `=> x + 83 = 155` `=> x = 155 – 83 = 72` b. `(x^2 – 18) : 63 = 1` `=> x^2 – 18 = 63` `=> x^2 = 63 + 18` `=> x^2 = 81` `=> x^2 = 9^2 = (-9)^2` `=> x = 9 ; x = -9` c. `5^(x + 1) + 5^x = 150` `=> 5^x . 5^1 + 5^x . 1 = 150` `=> 5^x . (5 + 1) = 150` `=> 5^x . 6 = 150` `=> 5^x = 25` `=> 5^x = 5^2` `=> x = 2` Reply
Bài 2:
a) 47.76 + 76.54 – 76
= 76. (47 + 54 -1)
= 76. 100
= 7600
b) {[260 – (36 -31)^3 . 2] -9} . 2017
= {[260 – 5^3 .2 ]-9 }.2017
= {[260 – 125.2] -9}.2017
={[260 – 250] -9}.2017
= {10-9}.2017
= 1.2017
= 2017
c) 11. 2^3 + 3^3. 2 – 29
= 11. 8 + 27.2 -29
= 88 + 54 – 29
= 113
Bài 3:
a) 491 – (x+83) = 336
x+83 = 491 – 336
x+83 = 155
x = 155 – 83
x = 72
b) (x^2 -18) : 63 = 1
x^2 -18 = 1. 63 = 63
x^2 = 63+18 =81
Mà 9^2 = 81
=> x = 9
c) 5^x+1 +5^x = 150
5^x. 5 + 5^x = 150
5^x . (5+1) = 150
5^x .6 = 150
5^x =150 : 6= 25
Mà 5^2 = 25
=> x = 5
Bài 2:
a. `47 . 76 + 76 . 54 – 76`
`= 76 . (47 + 54 – 1)`
`= 76 . 100 = 7600`
b. `{[260 – (36 – 31)^3 . 2] – 9} . 2017`
`= {[260 – 5^3 . 2] – 9} . 2017`
`= {[260 – 250] – 9} . 2017`
`= {10 – 9} . 2017`
`= 1 . 2017 = 2017`
c. `11 . 2^3 + 3^3 . 2 – 29`
`= 11 . 8 + 27 . 2 – 29`
`= 88 + 54 – 29`
`= 142 – 29 = 114`
Bài 3:
a. `491 – (x + 83) = 336`
`=> x + 83 = 491 – 336`
`=> x + 83 = 155`
`=> x = 155 – 83 = 72`
b. `(x^2 – 18) : 63 = 1`
`=> x^2 – 18 = 63`
`=> x^2 = 63 + 18`
`=> x^2 = 81`
`=> x^2 = 9^2 = (-9)^2`
`=> x = 9 ; x = -9`
c. `5^(x + 1) + 5^x = 150`
`=> 5^x . 5^1 + 5^x . 1 = 150`
`=> 5^x . (5 + 1) = 150`
`=> 5^x . 6 = 150`
`=> 5^x = 25`
`=> 5^x = 5^2`
`=> x = 2`