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

Transcript

Example 5 Simplify the expressions and evaluate them as directed: (i) π‘₯ (π‘₯βˆ’3)+2 for π‘₯=1 π‘₯ (π‘₯βˆ’3)+2=π‘₯Γ—π‘₯βˆ’π‘₯Γ—3+2 =π‘₯^2βˆ’3π‘₯+2 For x = 1 Putting x = 1 in expression π‘₯^2βˆ’3π‘₯+2 = 1^2βˆ’3Γ—1+2 = 1βˆ’3+2 = (1+2)βˆ’3 = 3βˆ’3 = 𝟎 Example 5 Simplify the expressions and evaluate them as directed: (ii) 3𝑦(2π‘¦βˆ’7)βˆ’3(π‘¦βˆ’4)βˆ’63 for 𝑦=βˆ’2 3𝑦(2π‘¦βˆ’7)βˆ’3(π‘¦βˆ’4)βˆ’63 =3𝑦×2π‘¦βˆ’3𝑦×7βˆ’3×𝑦+3Γ—4βˆ’63 =6𝑦^2βˆ’21π‘¦βˆ’3𝑦+12βˆ’63 =6𝑦^2βˆ’24π‘¦βˆ’51 For y = βˆ’πŸ Putting 𝑦=βˆ’2 in expression 6𝑦^2βˆ’24π‘¦βˆ’51 = 6(βˆ’2)^2βˆ’24(βˆ’2)βˆ’51 =6Γ—4+24Γ—2βˆ’51 = 24+48βˆ’51 = 72βˆ’51 = 𝟐𝟏

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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.