InterviewSolution
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InterviewSolution
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Expand (i)` (4a+5b)^3` (ii) ` (3a-2b)^3` |
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Answer» (i) Putting `4a=x,and 5b=y`, we get ` (4a +5b)^3=(x+y)^3` `=x^3+y^3xy(x+y)` `=(4a)^3+(5b)^3+(3xx4a xx 5b)(4a+5b)` ` =64a^3+125b^3+60ab(4a+5b)` `=64a^3+125b^3+24a^2b+300ab^2`. (ii) Putting `3a=x and 2b =y`, we get ` 3a-2b)^3=(x-y)^3` `=x^3-y^3-3xy (x-y)` `=(3a)^3-(2b)^3-(3xx3a xx 2b) (3a- 2b)` `=27a^3=8b^3-18ab(3a-2b)` `=27 a^3-8b^3-54a^2b+36ab^2`. |
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