Practicing Success
If $a = 2022, b = 2021$ and c = 2020, then value of $a^2 + b^2 + c^2 – ab – bc – ca$ is: |
2 4 3 1 |
3 |
We know that, (a – b)2 = a2 + b2 – 2ab Given, a = 2022 b = 2021 c = 2020 = Let, m= a2 + b2 + c2 – ab – bc – ca = Multiply both sides by 2 = 2m= 2(a2 + b2 + c2 – ab – bc – ca) = 2m = 2a2 + 2b2 + 2c2 – 2ab – 2bc – 2ca = 2m = a2 – 2ab + b2 + b2 – 2bc + c2 + c2 – 2ca + a2 = 2X = (a – b)2 + (b – c)2 + (c – a)2 = 2X = (2022 – 2021)2 + (2021 – 2020)2 + (2020 – 2022)2 = 2X = 1 + 1 + 4 = 6 = 2X = 6 = x = 3 |