Algebra · real student question

Solve (3/4)x - 3 = 0.

Question

Solve

34x3=0\frac{3}{4}x-3=0

Step-by-step solution

  1. Note that 34x3\tfrac34x-3 alone cannot be simplified. The two terms are unlike — 34x\tfrac34x carries a variable and 3-3 does not — so there is nothing to combine. It becomes a solvable problem only once it is set equal to something, here 00.

  2. Isolate the variable term. Add 33 to both sides:

    34x=3\frac{3}{4}x=3

  3. Multiply by the reciprocal instead of dividing by a fraction. The coefficient is 34\tfrac34, whose reciprocal is 43\tfrac43:

    4334x=433x=123=4\frac{4}{3}\cdot\frac{3}{4}x=\frac{4}{3}\cdot3\qquad\Longrightarrow\qquad x=\frac{12}{3}=4

    Multiplying by 43\tfrac43 is cleaner than dividing by 34\tfrac34, and it makes the cancellation 4334=1\tfrac43\cdot\tfrac34=1 visible.

  4. Alternative: clear the denominator first. Multiplying the whole equation by 44 at the very start gives 3x12=03x-12=0, hence 3x=123x=12 and x=4x=4 ✓ — the same answer with no fractions at all. Either route is fine; clearing denominators scales better when several fractions appear.

  5. Verify in the original equation. 34(4)3=33=0\tfrac34(4)-3=3-3=0 ✓, checked in exact rational arithmetic. Geometrically, y=34x3y=\tfrac34x-3 is a line of slope 34\tfrac34 with yy-intercept 3-3, and x=4x=4 is precisely where it crosses the xx-axis.

Answer

x=4x=4

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