# Example 5 - Chapter 9 Class 8 Algebraic Expressions and Identities

Last updated at Dec. 24, 2018 by Teachoo

Last updated at Dec. 24, 2018 by Teachoo

Transcript

Example 5 Simplify the expressions and evaluate them as directed: (i) ๐ฅ (๐ฅโ3)+2 for ๐ฅ=1 ๐ฅ (๐ฅโ3)+2=๐ฅร๐ฅโ๐ฅร3+2 =๐ฅ^2โ3๐ฅ+2 For x = 1 Putting x = 1 in expression ๐ฅ^2โ3๐ฅ+2 = 1^2โ3ร1+2 = 1โ3+2 = (1+2)โ3 = 3โ3 = ๐ Example 5 Simplify the expressions and evaluate them as directed: (ii) 3๐ฆ(2๐ฆโ7)โ3(๐ฆโ4)โ63 for ๐ฆ=โ2 3๐ฆ(2๐ฆโ7)โ3(๐ฆโ4)โ63 =3๐ฆร2๐ฆโ3๐ฆร7โ3ร๐ฆ+3ร4โ63 =6๐ฆ^2โ21๐ฆโ3๐ฆ+12โ63 =6๐ฆ^2โ24๐ฆโ51 For y = โ๐ Putting ๐ฆ=โ2 in expression 6๐ฆ^2โ24๐ฆโ51 = 6(โ2)^2โ24(โ2)โ51 =6ร4+24ร2โ51 = 24+48โ51 = 72โ51 = ๐๐

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