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Ex 14.1, 2 (vii) - Factorise 10 a^2 - 15 b^2 + 20 c^2 - Teachoo

Ex 14.1, 2 (vii) - Chapter 14 Class 8 Factorisation - Part 2
Ex 14.1, 2 (vii) - Chapter 14 Class 8 Factorisation - Part 3

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Transcript

Ex 14.1, 2 (Method 1) Factorise the following expressions. (vii) 10 𝑎^2 – 15 𝑏^2 + 20 𝑐^2 Now, 10𝑎^2= 10 × 𝑎^2 = 2 × 5 × 𝑎^2 = 2 × 5 × a × a 15𝑏^2 = 15 × 𝑏^2 = 3 × 5 × 𝑏^2 = 2 × 5 × b × b 20𝑐^2 = 20 × 𝑐^2 = 2 × 2 × 5 × 𝑐^2 = 2 × 2 × 5 × c × c So, 5 is the common factor. 10𝑎^2 – 15𝑏^2 + 20𝑐^2 = (2 × 5 × a × a) − (3 × 5 × b × b) + (2 × 2 × 5 × c × c) Taking 5 common = 5 × ((2 × a × a) − (3 × b × b) + (2 × 2 × c × c)) = 5 × (2𝑎^2 − 3𝑏^2 + 4𝑐^2) = 5 (2𝒂^𝟐 − 3𝒃^𝟐 + 4𝒄^𝟐) Ex 14.1, 2 (Method 2) Factorise the following expressions. (vii) 10 𝑎^2 – 15 𝑏^2 + 20 𝑐^2 10 𝑎^2 – 15 𝑏^2 + 20 𝑐^2 = (5 × 2) 𝑎^2 − (5 × 3 ) 𝑏^2 + (5 × 4) 𝑐^2 Taking 5 common, = 5 (2𝒂^𝟐 − 3𝒃^𝟐 + 4𝒄^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.