JAMB - Mathematics (2015 - No. 60)
Rationalize 5 ÷ (2 − √3)
3(2 + √5)
2(3 + √5)
5(2 + √3)
3 √2 + 1
คำอธิบาย
5÷ (2 − √3)
Using conjugate surds
[5 ÷ (2 − √3)]×(2 + √3) ÷ (2 + √3)]
[5(2+√3)÷((2− √3))2]
[5(2 +√3) ÷ (2)2− (√3)2]
[5(2 +√3) ÷(4− 3)]
= 5(2 + √3)
Using conjugate surds
[5 ÷ (2 − √3)]×(2 + √3) ÷ (2 + √3)]
[5(2+√3)÷((2− √3))2]
[5(2 +√3) ÷ (2)2− (√3)2]
[5(2 +√3) ÷(4− 3)]
= 5(2 + √3)