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  1. Chapter 9 Class 8 Algebraic Expressions and Identities
  2. Serial order wise

Transcript

Ex 9.5, 3 Find the following squares by using the identities. (i) (π‘βˆ’7)^2 (π‘βˆ’7)^2 (π‘₯βˆ’π‘¦)^2=π‘₯^2+𝑦^2βˆ’2π‘₯𝑦 Putting π‘₯ = 𝑏 & 𝑦 = 7 = (𝑏)^2+(7)^2βˆ’2(𝑏)(7) = 𝑏^2+49βˆ’(2Γ—7)×𝑏 = 𝒃^𝟐+πŸ’πŸ—βˆ’πŸπŸ’π’ƒ Ex 9.5, 3 Find the following squares by using the identities. (ii) (π‘₯𝑦+3𝑧)^2 (π‘₯𝑦+3𝑧)^2 (π‘Ž+𝑏)^2=π‘Ž^2+𝑏^2+2π‘Žπ‘ Putting π‘Ž = π‘₯𝑦 & 𝑏 = 3𝑧 = (π‘₯𝑦)^2+(3𝑧)^2+2(π‘₯𝑦)(3𝑧) = (π‘₯^2×𝑦^2 )+(3^2×𝑧^2 )+(2Γ—3)Γ—(π‘₯×𝑦×𝑧) = 𝒙^𝟐 π’š^𝟐+πŸ—π’›^𝟐+πŸ”π’™π’šπ’› Ex 9.5, 3 Find the following squares by using the identities. (iii) (6π‘₯^2βˆ’5𝑦)^2 (6π‘₯^2βˆ’5𝑦)^2 (π‘Žβˆ’π‘)^2=π‘Ž^2+𝑏^2βˆ’2π‘Žπ‘ Putting π‘Ž = 6π‘₯^2 & 𝑏 = 5𝑦 = (6π‘₯^2 )^2+(5𝑦)^2βˆ’2(6π‘₯^2 )(5𝑦) = (6^2Γ—π‘₯^(2 Γ— 2) )+(5^2×𝑦^2 )βˆ’(2Γ—6Γ—5)Γ—(π‘₯^2×𝑦) = (36Γ—π‘₯^4 )+(25×𝑦^2 )βˆ’(60Γ—π‘₯^2 𝑦) = πŸ‘πŸ”π’™^πŸ’+πŸπŸ“π’š^πŸβˆ’πŸ”πŸŽπ’™^𝟐 π’š Ex 9.5, 3 Find the following squares by using the identities. (iv) (2/3 π‘š+3/2 𝑛)^2 (2/3 π‘š+3/2 𝑛)^2 (π‘Ž+𝑏)^2=π‘Ž^2+𝑏^2+2π‘Žπ‘ Putting π‘Ž = 2/3 π‘š & 𝑏 = 3/2 𝑛 = (2/3 π‘š)^2+(3/2 𝑛)^2+2(2/3 π‘š)(3/2 𝑛) = (2/3)^2Γ—π‘š^2+(3/2)^2×𝑛^2+((2 Γ— 2 Γ— 3)/(3 Γ— 2))Γ—(π‘šΓ—π‘›) = πŸ’/πŸ— π’Ž^𝟐+ πŸ—/πŸ’ 𝒏^𝟐+πŸπ’Žπ’ Ex 9.5, 3 Find the following squares by using the identities. (v) (0.4π‘βˆ’0.5π‘ž)^2 (0.4π‘βˆ’0.5π‘ž)^2 (π‘Žβˆ’π‘)^2=π‘Ž^2+𝑏^2βˆ’2π‘Žπ‘ Putting π‘Ž = 0.4𝑝 & 𝑏 = 0.5π‘ž = (0.4𝑝)^2+(0.5π‘ž)^2βˆ’2(0.4𝑝)(0.5π‘ž) = (4/10)^2×𝑝^2+(5/10)^2Γ—π‘ž^2βˆ’(2Γ—4/10Γ—5/10)Γ—(π‘Γ—π‘ž) = 16/100 𝑝^2+ 25/100 π‘ž^2βˆ’4/10 π‘π‘ž = 𝟎.πŸπŸ”π’‘^𝟐+𝟎.πŸπŸ“π’’^πŸβˆ’πŸŽ.πŸ’π’‘π’’ Ex 9.5, 3 Find the following squares by using the identities. (vi) (2π‘₯𝑦+5𝑦)^2 (2π‘₯𝑦+5𝑦)^2 (π‘Ž+𝑏)^2=π‘Ž^2+𝑏^2+2π‘Žπ‘ Putting π‘Ž = 2π‘₯𝑦 & 𝑏 = 5𝑦 = (2π‘₯𝑦)^2+(5𝑦)^2+2(2π‘₯𝑦)(5𝑦) = (2^2Γ—π‘₯^2×𝑦^2 )+(5^2×𝑦^2 )+(2Γ—2Γ—5)Γ—π‘₯Γ—(𝑦×𝑦) = πŸ’π’™^𝟐 π’š^𝟐+πŸπŸ“π’š^𝟐+πŸπŸŽπ’™π’š^𝟐

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.