Algebra · real student question

Solve the inequality x - 3(x - 2) >= 4.

Question

Solve

x3(x2)4x-3(x-2)\ge 4

Step-by-step solution

  1. Distribute 3-3, not 33. The bracket carries a minus sign in front of the 33, so both inner terms are multiplied by 3-3:

    3(x2)=3x+6-3(x-2)=-3x+6

    The sign of the second term is the trap: 3×(2)=+6-3\times(-2)=+6.

  2. Rewrite and combine like terms.

    x3x+642x+64x-3x+6\ge 4\quad\Longrightarrow\quad -2x+6\ge 4

  3. Isolate the variable term. Subtract 66 from both sides:

    2x2-2x\ge -2

  4. Divide by 2-2 and reverse the inequality.

    x1x\le 1

  5. Check three values. At x=1x=1: 13(1)=1+3=441-3(-1)=1+3=4\ge 4 \checkmark (endpoint included). At x=2x=-2: 23(4)=2+12=104-2-3(-4)=-2+12=10\ge 4 \checkmark. At x=5x=5: 53(3)=4≱45-3(3)=-4\not\ge 4 \checkmark. Solution set: (,1](-\infty,1].

Answer

x1,i.e. (,1]x\le 1,\qquad\text{i.e. }(-\infty,1]

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