Question

5. If a²-a-10 = 0. Then (a+1) (a+2) (a-4) is ,_______​

Answer 1

Answer:

The answer is -8

Step-by-step explanation:

Given $a^2-a-10=0$

       $\Rightarrow a^2=a+10$ ....(1)

Therefore  $(a+1)(a+2)(a-4)$

               $=(a^2+3a+2)(a-4)\\=(a+10+3a+2)(a-4)$, using (1)

              $=(4a+12)(a-4)\\=4(a+3)(a-4)\\=4(a^2-a-12)$

               $=4(a+10-a-12)\\=4(-2)=-8$, using (1)