Ex 12.2, 1 (vii) - Factorise (l + m)^2 - 4lm (Hint: Expand (l+m)^2 - Ex 12.2

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Ex 12.2, 1 Factorise the following expressions. (vii) 〖"(l + m)" 〗^2 – 4lm (Hint: Expand 〖"(l + m)" 〗^2 first)〖"(l + m)" 〗^2 – 4lm = 𝑙^2+𝑚^2+2𝑙𝑚 −4𝑙𝑚 = 𝑙^2+𝑚^2+𝑙𝑚 (2−4) = 𝒍^𝟐+𝒎^𝟐−𝟐𝒍𝒎 = (𝒍−𝒎)^𝟐 Using (𝒂+𝒃)^𝟐=𝑎^2+𝑏^2+2𝑎𝑏 Here, 𝑎 = l and b = m Using (𝒂−𝒃)^𝟐=𝑎^2+𝑏^2−2𝑎𝑏 Here, 𝑎 = l and b = m

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