Question
Write $(3 a+4 b)^3$ in the expanded form.
✓
Answer
Comparing the given expression with $(x+y)^3$,
we find that $x=3$ a and $y=4 b$.
So, using Identity $(x+y)^3=x^3+y^3+3 x y(x+y)$,
we have: $(3 a+4 b)^3=(3 a)^3+(4 b)^3+3(3 a)(4 b)(3 a+4 b)$
$=27 a^3+64 b^3+108 a^2 b+144 a b^2$
This is the required expansion.
we find that $x=3$ a and $y=4 b$.
So, using Identity $(x+y)^3=x^3+y^3+3 x y(x+y)$,
we have: $(3 a+4 b)^3=(3 a)^3+(4 b)^3+3(3 a)(4 b)(3 a+4 b)$
$=27 a^3+64 b^3+108 a^2 b+144 a b^2$
This is the required expansion.
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