## helpppppppppppppppppppppppppppppppppppppppp

Question

helpppppppppppppppppppppppppppppppppppppppp

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9 months 2021-05-10T18:40:47+00:00 2 Answers 12 views 0

1. Đáp án + Giải thích các bước giải:

a) 3x – 8 = 2(x – 4) + 5 $\\$ <=> 3x-8=2x-8+5 $\\$ <=>3x-8-2x+8-5=0 $\\$ <=>x – 5 = 0 <=> x = 5

Vậy S = {5}

b) x^2 + 5x – 6 = 0 $\\$ <=> x^2-x + 6x – 6 = 0 $\\$ <=> x(x – 1) + 6(x – 1) = 0 $\\$ <=> (x – 1)(x + 6) = 0 <=> $$\left[ \begin{array}{l}x=1\\x=-6\end{array} \right.$$

Vậy S = {1;-6}

c) 3/(x + 1) – 2/(x – 2) = (4x – 2)/[(x + 1)(x – 2)](x ne -1,x ne 2) $\\$ <=> [3(x – 2)]/[(x+1)(x-2)] – [2(x+1)]/[(x+1)(x-2)] = (4x – 2)/[(x + 1)(x – 2)] $\\$ => 3(x – 2) – 2(x + 1) = 4x – 2 $\\$ <=> 3x – 6 – 2x – 2 – 4x + 2 = 0 $\\$ <=> -3x – 6 = 0 $\\$ <=> -3x = 6 <=> x = -2(TMĐK)

Vậy S = {-2}

d) |2x – 5| = x + 2

<=> $$\left[ \begin{array}{l}2x-5=x+2\\-(2x-5)=x+2\end{array} \right.$$ $\\$ <=>  $$\left[ \begin{array}{l}2x-5-x-2=0\\-2x+5-x-2=0\end{array} \right.$$ $\\$ <=>  $$\left[ \begin{array}{l}x-7=0\\-3x + 3 = 0\end{array} \right.$$ $\\$ <=> $$\left[ \begin{array}{l}x=7\\x = 1\end{array} \right.$$

Vậy S = {7;1}

2. Đây nhé bạn chúc bạn học tốt ^^