Solve for :
Distribute the over the bracket. Both terms inside are affected:
since . Keeping the minus sign attached to the fraction is what makes the next steps come out right.
Combine the constants on the left.
Isolate the term. Subtract from both sides — an addition, so the direction is untouched:
Multiply by and reverse the inequality. This is the crux: multiplying or dividing by a negative number flips into :
Leaving it as would give exactly the wrong half of the line.
Test three points to be sure. At : , and holds (so the endpoint is included). At : ✓. At : , and is false ✓. So the solution is , i.e. .
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