Question

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

• A. $-\frac{3}{2}$
• B. $-\frac{1}{2}$
• C. $-\frac{3}{7}$
• D. $-\frac{3}{8}$

Answer 1

The correct option is A $-\frac{3}{2}$

We have, $3x\times (4x-5)+3=3\times 4x-3x\times 5+3$
$=12x^2-15x+3$
When $x=\frac{1}{2}$,

$3x(4x-5)+3$ $=3\times \frac{1}{2}(4\times \frac{1}{2}-5)+3$
= $\frac{3}{2}\times -3+3=-\frac{9}{2}+3=-\frac{3}{2}$