#KhanhHuyen2006 - Xin câu trả lời hay nhất
Bài 7
`a) (x - 12) - (-72 + 26) = 0`
`→ (x - 12) - (-46) = 0`
`→ x - 12 = -46`
`→ x = -34`
`b) 5^2 - (12 - x) = 10`
`→ 25 - (12 - x) = 10`
`→ 12 - x = 15`
`→ x = -3`
`c) - (x + 2) + 24 = (-5)^2
`→ x - 2 + 24 = 25`
`→ x - 2 = 1`
`→ x = 3`
`d) - (24 - 10 - x) - 3^2 = 12 - (7 - 10)`
`→ 24 + 10 + x - 9 = 12 - (-3)`
`→ 24 + 10 + x - 9 = 15`
`→ 24 + 10 + x = 24`
`→ 10 + x = 0`
`→ x = -10`
`e) (5 - 7)^2 - (-1 - x) = (-3)^2`
`→ (-2)^2 - (-1 - x) = 9`
`→ 4 - (-1 - x) = 9`
`→ -1 - x = -5`
`→ x = 4`
`f) (x - 2) - (1 - x) = (-2)^3 + |-9|`
`→ x - 2 - 1 - x = -8 + 9`
`→ 2x - 3 = 1`
`→ 2x = 4`
`→ x = 2`
Bài 8
`a) |2x - 1| + (-2)^2 = 15 - 20`
`→ |2x - 1| + 4 = -5`
`→ |2x - 1| = -9`
`→ x = ∅`
`b) 7 - |x - 1| = (-2) . (-5) - 8`
`→ 7 - |x - 1| = 10 - 8`
`→ 7 - |x - 1| = -2`
`→ |x - 1| = 9`
`→ x - 1 = 9` hoặc `x - 1 = -9`
`→ x = 10` hoặc `x = -8`
`c) |x + 2| - 3^2 = |5 - 9|`
`→ |x + 2| - 9 = |-4|`
`→ |x + 2| - 9 = 4`
`→ |x + 2| = 13`
`→ x + 2 = 13` hoặc `x + 2 = -13`
`→ x = 11` hoặc `x = -15`
`d) 2 . |4 - x| - 5 = -1^2`
`→ 2 . |4 - x| - 5 = 1`
`→ 2 . |4 - x| = 6`
`→ |4 - x| = 3`
`→ 4 - x = 3` hoặc `4 - x = -3`
`→ x = 1` hoặc `x = 7`
`e) 1 - |1 - x| : 2 = (-1)^2`
`→ 1 - |1 - x| : 2 = 1`
`→ |1 - x| : 2 = 0`
`→ |1 - x| = 0`
`→1 - x = 0 → x = 1`
`f) -2^3 + 12 : |x + 5| = -5`
`→ -8 + 12 : |x + 5| = -5`
`→ 12 : |x + 5| = 3`
`→ |x + 5| = 4`
`→ x + 5 = 4` hoặc `x + 5 = -4`
`→ x = -1` hoặc `x = -9`
Bài 9
`a) 16 + 5x^2 = -11`
`→ 5x^2 = 5`
`→ x^2 = 1`
`→ x^2 = 1^2`
`→ x = 1`
`b) -9 - x^2 = -5^2`
`→ -9 - x^2 = -25`
`→ x^2 = 16`
`→ x^2 = (±4)^2`
`→ x = ±4`
`c) -36 + (4 - x)^2 = (-3)^3`
`→ -36 + (4 - x)^2 = -27`
`→ (4 - x)^2 = 9`
`→ (4 - x)^2 = 3^2` hoặc `(4 - x)^2 = (-3)^2`
`→ 4 - x = 3` hoặc `4 - x = -3`
`→ x = 1` hoặc `x = 7`
`d) (-4)^3 + 5 . (2x + 2)^2 = (-4)^2`
`→ -64 + 5 . (2x + 2)^2 = 16`
`→ 5 . (2x + 2)^2 = 80`
`→ (2x + 2)^2 = 16`
`→ (2x + 2)^2 = 4^2` hoặc `(2x + 2)^2 = (-4)^2`
`→ 2x + 2 = 4` hoặc `2x + 2 = -4`
`→ 2x = 2` hoặc `2x = -6`
`→ x = 1` hoặc `x = -3`
`e) 4^2 - 2 . (x + 5)^2 = (-2) . (-4)`
`→ 16 - 2 . (x + 5)^2 = 8`
`→ 2 . (x + 5)^2 = 8`
`→ (x + 5)^2 = 4`
`→ (x + 5)^2 = 2^2` hoặc `(x + 5)^2 = (-2)^2`
`→ x + 5 = 2` hoặc `x + 5 = -2`
`→ x = -3` hoặc `x = -7`
`f) 28 - (10 + x^3) = 10`
`→ 10 + x^3 = 18`
`→ x^3 = 8`
`→ x^3 = 2^3`
`→ x = 2`
