If (a=\sqrt{5}+3) and (b=\sqrt{5}-3), what is the value of (ab)?
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Answer and explanation
Correct answer: (-4)
Step 1: (ab=(\sqrt{5}+3)(\sqrt{5}-3)). Step 2: Using difference of squares, ((\sqrt{5})^2-3^2=5-9=-4). Step 3: Recognising conjugate form makes the calculation shorter.
Frequently asked questions
What is the correct answer to this question?
(-4)
Why is this the correct answer?
Step 1: (ab=(\sqrt{5}+3)(\sqrt{5}-3)). Step 2: Using difference of squares, ((\sqrt{5})^2-3^2=5-9=-4). Step 3: Recognising conjugate form makes the calculation shorter.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Real Numbers. Topic: Irrational numbers.
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