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√(16-x^2) - √(4+x^2) = 2==> [√(16 - x^2) - √(4+x^2)]^2 = 2^2==> [√(16 - x^2)]^2 - 2 * [√(16 - x^2) *√(4+x^2)] + [√(4+x^2)]^2 = 2^2==> (16 - x^2) - 2 [√(16 - x^2) *√(4+x^2)] + (4 +x^2) = 4==> 20 - 2 [√(16 - x^2) *√(4+x^2)] = 4==> √(16 - x^2) *√(4+x^2) = 8 √(16-x^2) + √(4+x^2) = √[√(16-x^2) +√(4+x^2)] ^2= √{[√(16 - x^2)]^2 + 2 * [√(16 - x^2) *√(4+x^2)] + [√(4+x^2)]^2}= √{ (16 - x^2) + 2 [√(16 - x^2) *√(4+x^2)] + (4 +x^2)}= √{20 + 2 [√(16 - x^2) *√(4+x^2)] }= √{20 + 2 * 8}= √36= 6
1年前
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