Question

Find value of $3x(4x-5)+3$ at,

(i) $x=3$

(ii) $x=\frac{1}{2}$

Answer 1

at $x=3\Rightarrow 3\left(3\right)\left(4\right(3)-5)+3$

$=9(12-5)+3=9\times 7+3=66$

at $x=\frac{1}{2}\Rightarrow 3\left(\frac{1}{2}\right)\left(4\right(\frac{1}{2})-5)+3$

$=\frac{3}{2}(2-5)+3$

$=\frac{3}{2}\times (-3)+3$

$=\frac{-9}{2}+3=\frac{-3}{2}$