Question 1 - Figure it out - Page 154-156 - Chapter 6 Class 8 - We Distribute yet things Multiply (Ganita Prakash)

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Question 1 Compute these products using the suggested identity. (i) 462 using Identity 1A for (a + b)2We can write 46 = (40 + 6) Now, 〖𝟒𝟔〗^𝟐=(40+6)^2 Using (a + b)2 = a2 + 2ab + b2 =40^2+2 × 40 × 6+6^2 =1600+480+36 =𝟐𝟏𝟏𝟔 Question 1 Compute these products using the suggested identity. (ii) 397 × 403 using Identity 1C for (a + b) (a – b)Now, 𝟑𝟗𝟕 × 𝟒𝟎𝟑=(𝟒𝟎𝟎−𝟑) ×(𝟒𝟎𝟎+𝟑) Using (a + b)(a – b) = a2 – b2 =400^2−3^2 =1,60,000−9 =𝟏,𝟓𝟗,𝟗𝟗𝟏 Question 1 Compute these products using the suggested identity. (iii) 912 using Identity 1B for (a – b)2We can write 91 = (100 – 9) Now, 〖𝟗𝟏〗^𝟐=(100−9)^2 Using (a – b)2 = a2 – 2ab + b2 =100^2−2 × 100 × 9+9^2 =10,000−1,800+81 =10,081−1,800 =𝟖,𝟐𝟖𝟏 Question 1 Compute these products using the suggested identity. (iv) 43 × 45 using Identity 1C for (a + b) (a – b)Now, 𝟒𝟑 × 𝟒𝟓=(𝟒𝟒−𝟏) ×(𝟒𝟒+𝟏) Using (a + b)(a – b) = a2 – b2 =44^2−1^2 =1,936−1 =𝟏,𝟗𝟑𝟓