Quadratic functions and the discriminant Quiz

1. The equation $2x^2+4x+k=0$ has equal roots. Find $k$.

• A. $1$
• B. $2$
• C. $4$
• D. $8$

2. What is the minimum value of $x^2-8x+20$?

• A. $4$
• B. $20$
• C. $-4$
• D. $16$

3. For which values of $m$ does $x^2+mx+9=0$ have no real roots?

• A. $m<-6$ or $m>6$
• B. $m>6$
• C. $-3<m<3$
• D. $-6<m<6$

4. Solve $y^2-7y+10=0$ where $y=\sqrt{x}$. Find the solutions for $x$.

• A. $x=2,5$
• B. $x=4,25$
• C. $x=\pm2,\pm5$
• D. $x=10$

5. A quadratic curve touches the $x$-axis at one point. What is true of its discriminant?

• A. It is positive.
• B. It is negative.
• C. It is zero.
• D. It is $1$.