Algebra · real student question

Solve the inequality 2x - 7 < 3(x - 1).

Question

Solve

2x7<3(x1)2x-7<3(x-1)

Step-by-step solution

  1. Expand the right-hand bracket.

    3(x1)=3x32x7<3x33(x-1)=3x-3\quad\Longrightarrow\quad 2x-7<3x-3

  2. Subtract 2x2x from both sides. The bigger coefficient 33 is on the right, so the variable naturally ends up there with a positive coefficient:

    7<x3-7<x-3

  3. Add 33 to both sides.

    4<x-4<x

  4. Rewrite with the variable on the left. Swapping the two sides of an inequality reverses the symbol — it does not change the meaning:

    x>4x>-4

    This is bookkeeping, not the negative-division rule; both statements describe the same set (4,)(-4,\infty).

  5. Check three points. At x=0x=0: left =7=-7, right =3=-3, and 7<3-7<-3 \checkmark. At x=10x=-10: left =27=-27, right =33=-33, false \checkmark. At x=4x=-4: both sides equal 15-15, correctly excluded by the strict <<.

Answer

x>4,i.e. (4,)x>-4,\qquad\text{i.e. }(-4,\infty)

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