Question

A= 2+√7
b= 2-√7

Nilai a²+b²-4ab ?

Answer 1

A² + b² -4ab
= (2+√7)² + (2-√7)² - 4(2+√7)(2-√7)
=(1+4√7 +7) + (4-4√7+7) - 4(4-7) -- ingat (a+b)² = (a²+2ab+b²) dan (a-b)(a+b)=a²-b²
= (11+4√7) + (11 - 4√7) - (8 - 28)
= 22 + 20
=32