JAMB 1993 · UME · Q33

The three sides of an isosceles triangle are of lengths $x + 3$ , $2x + 3$ and $2x - 3$ . Calculate $x$ .

Worked solution (try it first)

Two of the sides are equal.
$2x + 3$ and $2x - 3$ can never be equal, so one of them equals $x + 3$ .
$x + 3 = 2x + 3$ gives $x = 0$ , which makes a side $-3$ : impossible.
$x + 3 = 2x - 3$ gives $x = 6$ , with sides 9, 15 and 9.
So $x = 6$ , option D.

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