Question

factorise a^3 - a - 120 . the answer is given in my book _ ie. (a - 5)(a^2 + 5a + 24) . please tell how this ans. came.....

Answer 1

Given Equation is a^3 - a - 120

= > a^3 - 5a^2 + 24a - 5a^2 - 25a - 120

= > a(a^2 + 5a + 24) - 5(a^2 + 5a + 24)

= > (a - 5)(a^2 + 5a + 24).



Hope this helps!

Answer 2

hey bro!
___________

Given that equation
==> a^3 -a -120 =0

so we find the factor of 120 which putting the value a, Gives us equation to = 0

so
we put the value of a= 5 which is factor of 120

Now

==> 5^3 -5 -120=0

==> 125 -5 -120=0

==> 125-125=0

==> 0=0

so (a-5) is factor of the equation

then

==> a^2(a-5) +5a(a-5) +24(a-5) =0

==>(a-5) (a^2 +5a +24) Ans!

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