Binomial stuff:
a The third term of [math](1\, +\, x)^n[/math] is [math]36x^2.[/math] Find the fourth term.
b If [math](1\, +\, kx)^n\, =\, 1\, -\, 12x\, +\, 60x^2\, -\, ...,[/math] find the values of [math]k[/math] and [math]n[/math].
c Find [math]a[/math] if the coefficient of [math]x^{11}[/math] in the expansion of [math]\left(x^2\, +\, \frac{1}{ax}\right)^{10}[/math] is 15.
I am stuck from the beginning. I tried using general term way:Tr+1,and gives me the equation of (n chooses 2)=36,and i don't know how to solve it
a The third term of [math](1\, +\, x)^n[/math] is [math]36x^2.[/math] Find the fourth term.
b If [math](1\, +\, kx)^n\, =\, 1\, -\, 12x\, +\, 60x^2\, -\, ...,[/math] find the values of [math]k[/math] and [math]n[/math].
c Find [math]a[/math] if the coefficient of [math]x^{11}[/math] in the expansion of [math]\left(x^2\, +\, \frac{1}{ax}\right)^{10}[/math] is 15.
I am stuck from the beginning. I tried using general term way:Tr+1,and gives me the equation of (n chooses 2)=36,and i don't know how to solve it
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