Question

(a) Simplify $3x(4x-5)+3$ and find its value for
(i) $x=3$ (ii) $x=\frac{1}{2}$

(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] (i) $3x(4x-5)+3$
$=3\times 3(4\times 3-5)+3$
$=9\left(7\right)+3=66$

(ii) $3x(4x-5)+3$
$=3\times \frac{1}{2}(4\times \frac{1}{2}-5)+3$
$=\frac{3}{2}(2-5)+3$
$=\frac{-3}{2}$

[b] (i) $a(a^2+a+1)+5$

$=0+5$
$=5$

(ii) $a(a^2+a+1)+5$
$=1\left(3\right)+5$
$=8$

(iii) $a(a^2+a+1)+5$
$-1(1-1+1)+5$
$-1+5$
$=4$