Question

evaluate using suitable identities (b-7) ^2​

Answer 1

As per the formula

(a - b)^2 = a^2 +2ab - b^2

(b - 7)^2

a = b, b = 7

(b - 7)^2 = b^2 + 2.b.7 - 7^2

Answer 2

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We know that,

⇝ (a - b)² = a² + b² - 2ab

Using the above identity , we get

⇝ (b - 7)²

⇝ b² + 7² - 2 × b × 7

⇝ b² + 49 - 14b (Ans)

Some Identities :

⇝ (a + b)² = a² + b² + 2ab

⇝ (a - b)² = a² + b² - 2ab (Used Here)

⇝ (a² - b²) = (a + b)(a - b)

⇝ (a + b + c)² = a² + b² + c² + 2ab + 2bc + 2ca

⇝ (a + b)³ = a³ + b³ + 3ab(a + b)

⇝ (a - b)³ = a³ - b³ - 3ab(a - b)

⇝ (a³ + b³) = (a + b)(a² - ab + b²)

⇝ (a³ - b³) = (a - b)(a² + ab + b²)

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