Đáp án:
Giải thích các bước giải:
`a)`
`(2x+3)^2 - (2x+1)(2x-1) = 22`
`⇔ 4x^2 + 12x + 9 - 4x^2 + 1 = 22`
`⇔ (4x^2-4x^2) + 12x + (9+1) = 22`
`⇔ 12x + 10 = 22`
`⇔ 12x = 12`
`⇔ x = 1`
Vậy `S = {1}`
`b)`
`(2x-1)^3-4x^2(2x-3)=5`
`⇔ 8x^3 - 12x^2 + 6x - 1 - 8x^3 + 12x^2 = 5`
`⇔ (8x^3-8x^3) + (12x^2-12x^2) + 6x -1 = 5`
`⇔ 6x - 1 = 5`
`⇔ 6x = 6`
`⇔ x = 1`
Vậy `S = {1}`
`c)`
`(x-3)^2 - 4 = 0`
`⇔ (x-3)^2 = 4`
`⇔ |x-3| = 2`
`⇔`\(\left[ \begin{array}{l}x-3=2\\x-3=-2\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=5\\x=1\end{array} \right.\)
Vậy `S = {1,5}`
`d)`
`(2x-1)^2 + (x+3)^2 - 5(x+7)(x-7) = 0`
`⇔ 4x^2 - 4x + 1 + x^2 + 6x + 9 - 5x^2 + 245 = 0`
`⇔ (4x^2-5x^2+x^2) + (6x-4x) + (245+9+1) = 0`
`⇔ 2x + 255 = 0`
`⇔ 2x = -255`
`⇔ x = -255/2`
Vậy `S = {-255/2}`
