Question

Question 4(b)
Simplify : $a(a^2+a+1)+5$ and find its value for (i) a=0 (ii) a=1 (iii) a=-1.

Answer 1

$a(a^2+a+1)+5=a\times a^2+a\times a+a\times 1+5=a^3+a^2+a+5$

(i) For $a=0$
$a^3+a^2+a+5=(0{)}^3+(0{)}^2+\left(0\right)+5$
$=0+0+0+5=5$
(ii) For $a=1$
$a^3+a^2+a+5=(1{)}^3+(1{)}^2+\left(1\right)+5$
$=1+1+1+5=8$
(iii) For $a=-1$
$a^3+a^2+a+5=(-1{)}^3+(-1{)}^2+(-1)+5$
$=-1+1+(-1)+5=-2+6=4$