1)Tính:
4.{624:[5+7.(72:23-6)]}-5.3
=4.{624:[5+7.(72:8-6]}-15
=4.{624:[5+7.(9-6)]}-15
=4.{624:[5+7.3]}-15
=4.{624:26}-15
=4.24-15
=81
2) Tìm x biết
a)108-x=32.7
108-x=224
x=108-224
x=-116
b)15-(5x-4):3=23
(5x-4):3=15-23
(5x-4):3=-8
5x-4=-8.3
5x-4=-24
5x=-24+4
5x=-20
x=-20:5
x=-4
Bài 1 :
4 . {624 :[5 + 7 . (72 : 23 - 6)]} - 5 . 3
= 4 . {624 :[ 5 + 7 . (72 : 8 - 6)]} - 15
= 4 . {624 : [5 + 7 . (9 - 6)]} - 15
= 4 . [624 : (5 + 7 . 3)] - 15
= 4 . [624 : (5 + 21)] - 15
= 4 . (624 : 26) - 15
= 4 . 24 - 15
= 96 - 15
= 81
1)
\(4.\left\{624:\left[5+7.\left(72:2^3-6\right)\right]\right\}-5.3\)
\(=4\left\{624:\left[5+7.\left(72:8-6\right)\right]\right\}-15\)
\(=4.\left\{624:\left[5+7.\left(7-6\right)\right]\right\}-15\)
\(=4\left\{624:\left[5+7.1\right]\right\}-15\)
\(=4.\left\{624:\left[5+7\right]\right\}-15\)
\(=4.\left\{624:12\right\}-15\)
\(=4.52-15\)
\(=208-15=193\)
Bài 2 :
a) \(108-x=32.7\)
\(108-x=224\)
\(x=108-224\)
\(x=-116\)
Vậy \(x=-116\) là giá trị cần tìm
b) \(15-\left(5x-4\right):3=23\)
\(\left(5x-4\right):3=15-23\)
\(\left(5x-4\right):3=-8\)
\(5x-4=\left(-8\right).3\)
\(5x-4=-24\)
\(5x=\left(-24\right)+4\)
\(5x=-20\)
\(x=-20:5\)
\(x=-4\)
Vậy \(x=-4\) là giá trị cần tìm
Bài 1:
\(4\cdot\left\{624:\left[5+7\cdot\left(72:2^3-6\right)\right]\right\}-5\cdot3\)
\(=4\cdot\left\{624:\left[5+7.\left(72:8-6\right)\right]\right\}-15\)
\(=4\cdot\left\{624:\left[5+7\cdot\left(9-6\right)\right]\right\}-15\)
\(=4\cdot\left\{624:\left[5+7\cdot3\right]\right\}-15\)
\(=4\cdot\left\{624:\left[5+21\right]\right\}-15\)
\(=4\cdot\left\{624:26\right\}-15\)
\(=4\cdot24-15\)
\(=96-15\)
\(=81\)
Bài 2:
a) \(108-x=32\cdot7\)
\(\Rightarrow108-x=224\)
\(\Rightarrow x=108-224\)
\(\Rightarrow x=-116\)
Vậy \(x=-116\).
b) \(15-\left(5x-4\right):3=23\)
\(\Rightarrow\left(5x-4\right):3=15-23\)
\(\Rightarrow\left(5x-4\right):3=-8\)
\(\Rightarrow5x-4=-8\cdot3\)
\(\Rightarrow5x-4=-24\)
\(\Rightarrow5x=-24+4\)
\(\Rightarrow5x=-20\)
\(\Rightarrow x=-20:5\)
\(\Rightarrow x=-4\)
Vậy \(x=-4\).
