What if we replace b by - b in (a + b)² = a² + 2ab + b²? Class 9
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What if we replace b by - b in (a + b)² = a² + 2ab + b²? Class 9
Question 2.
What if we replace b by - b in (a + b)² = a² + 2ab + b²? Class 9
Answer:
Replacing b by - b in (a + b)² = a² + 2ab + b², we get
(a - b)² = a² + 2a(-b) + (-b)² = a² - 2ab + b²
This is also an identity and can be used in a similar way for factorisation as (a + b)² = a² + 2ab + b².