1. √7 × √7 = √[7×7] = √[7²] = 7
2. √18 × √2 = √[18×2] = √36 = √[6²] = 6
3. √45 = √[9×5] = √9 × √5 = √[3²] × √5 = 3√5
4. [tex]\dfrac{\sqrt{50}}{5}=\dfrac{\sqrt{25\cdot2}}{5}=\dfrac{\sqrt{25}\cdot\sqrt2}{5}=\dfrac{5\cdot\sqrt2}{5}=\bold{\sqrt2}[/tex]
5. 2√2 × 4√5 = (2×4) × (√2×√5) = 8×√[2×5] = 8√10
6. √48 - √12 = √[16×3] - √[4×3] = √16×√3 - √4×√3 = 4√3 - 2√3 = 2√3
7. (2 - √3)(1 + √3) = 2×1 + 2×√3 + (-√3)×1 + (-√3)×√3 =
= 2 + 2√3 - √3 - √[3×3] = 2 + √3 - 3 = √3 - 1
