√128 = one leg

x = other leg

3x = hypotenuse

Pythagorean Theorem is a² + b² = c²

a and b are the legs and c is the hypotenuse

x² + (√128)² = (3x)²

x² + 128 = 9x² {evaluated exponents}

128 = 8x² {subtracted x² from each side}

x² = 16 {divided each side by 8}

x = 4 {took square root of each side}

3x = 12 {substituted 4, in for x, into 3x}

**the leg is 4
**

the hypotenuse is 12*- Algebra House*
**
**