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Question : 135 of 180
Marks:
+1,
-0
Solution:
We have,
‌‌{(‌)7−(‌)7}=‌‌{(1+√(3x+1))7−(1−√(3x+1))7} . . . (i)
Now,
(1+√3x+1)7−(1−√3x+1)7[‌7C0+‌7C1√(3x+1)+‌7C2(√3x+1)2+.‌−[‌7C0−‌7C1√3x+1+‌7C2(√3x+1))2‌‌‌....−‌7C7(√3x+1)7]‌=2[‌7C1(√3x+1)7]‌‌‌+‌7C5(√3x+1)5+‌7C7(√3x+1)7]‌=2√3x+1×[7+35(3x+1)‌‌‌+21(3x+1)2+(3x+1)3]Now, putting above value in Eq. (i), so the given expression becomes
‌[42+105x+21(3x+1)2+(3x+1)3]So, degree of
x in given expression is 3 .
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