please answer this question
Answers
Answer:
Step-by-step explanation:
Answer:
Step-by-step explanation:
a=2-√5 and b=2+√5
2+√5 2-√5
a=2-√5 × 2-√5 and b=2+√5 × 2+√5
2+√5 2-√5 2-√5 2+√5
a=(2-√5)² and b=(2+√5)²
(2)²-(√5)² (2)²-(√5)²
a=4+5-4√5 and b=4+5+4√5
4-5 4-5
a=9-4√5 and b=9+4√5
-1 -1
a=-(9-4√5) and b=-(9+4√5)
a=-9+4√5 and b=-9-4√5
we know that
(a+b)(a-b)
=a²-b²
=((-9+4√5)-(-9-4√5))((-9+4√5)+(-9-4√5))
=(-9+4√5+9+4√5)(-9+4√5-9-4√5)
=(8√5)(-18)
=8√5×-18
=-321.99