Question

If $4a^2-4b=5$ and $a=\frac{1}{2}$, then the value of $b$ is

• A. $-2$
• B. $-1$
• C. $0$
• D. $1$
• E. $2$

Answer 1

Answer: (B)

$-1$

Given, $4a^2-4b=5$ and $a=\frac{1}{2}$

Putting value of $a$, we get

$4{\left(\frac{1}{2}\right)}^2-4b=5$

$\Rightarrow 4\times \frac{1}{4}-4b=5$

$\Rightarrow 1-4b=5$

$\Rightarrow 4b=-4$

$\to b=-1$