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Ex 9.4, 3 (vii) - Simplify (1.5x - 4y)(1.5x + 4y + 3) - 4.5x + 12y

Ex 9.4, 3 (vii) - Chapter 9 Class 8 Algebraic Expressions and Identities - Part 2
Ex 9.4, 3 (vii) - Chapter 9 Class 8 Algebraic Expressions and Identities - Part 3

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Transcript

Ex 9.4, 3 Simplify. (vii) (1.5𝑥−4𝑦)(1.5𝑥+4𝑦+3)−4.5𝑥+12𝑦 Here, there are 2 expressions: First expression = (1.5𝑥−4𝑦)(1.5𝑥+4𝑦+3) Second expression = 4.5𝑥+12𝑦 Solving First expression (1.5𝑥−4𝑦)(1.5𝑥+4𝑦+3) = 1.5𝑥(1.5𝑥+4𝑦+3)−4𝑦(1.5𝑥+4𝑦+3) = (1.5𝑥×1.5𝑥)+(1.5𝑥×4𝑦)+(1.5𝑥×3)−(4𝑦×1.5𝑥) −(4𝑦×4𝑦)+(4𝑦×3) = (15/10×15/10) 𝑥^2+(15/10×4)𝑥𝑦+(15/10×3)𝑥−(4×15/10)𝑦𝑥 −16𝑦^2+12𝑦 = (225/100) 𝑥^2+(60/10)𝑥𝑦+(45/10)𝑥−(60/10)𝑦𝑥−16𝑦^2+12𝑦 = 2.25𝑥^2+6𝑥𝑦+4.5𝑥−6𝑦𝑥−16𝑦^2+12𝑦 = 2.25𝑥^2−16𝑦^2+4.5𝑥−12𝑦+6𝑥𝑦−6𝑥𝑦 = 2.25𝑥^2−16𝑦^2+4.5𝑥−12𝑦 Now, our equation becomes (1.5𝑥−4𝑦)(1.5𝑥+4𝑦+3)−4.5𝑥+12𝑦 = 2.25𝑥^2−16𝑦^2+4.5𝑥−12𝑦−4.5𝑥+12𝑦 = 2.25𝑥^2−16𝑦^2+4.5𝑥−4.5𝑥−12𝑦+12𝑦 = 𝟐.𝟐𝟓𝒙^𝟐−𝟏𝟔𝒚^𝟐

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.