Question

If $b^2-4ac=0$ then the graph of $y=a{x}^2+bx+c$

• A. cuts x-axis in two real points.
• B. touches the x-axis.
• C. lies entirely above the x-axis.
• D. can not be determined.

Answer 1

Answer: (B)

touches the x-axis.

Given $b^2-4ac=0\Rightarrow$ the equation $a{x}^2+bx+c=0$ has two equal roots .
$\therefore$ the graph $y=a{x}^2+bx+c$ touches $x$-axis at the point having equal root.