MCQ
Which of the following equations has no real roots?
- A$x^2=10 x-2$
- B$x^2-12 x=16$
- C$7 x^2-1=-8 x$
- ✓$2 x^2+5 x+5=0$
✓
Answer
Correct option: D.
$2 x^2+5 x+5=0$
(d) : To have no real roots, discriminant $\left(D=b^2-4 a c\right)$ must be $<0$.
(a) $D=(-10)^2-4(1)(2)=100-8=92>0$
(b) $D=(-12)^2-4(1)(-16)=144+64=208>0$
(c) $D=(8)^2-4(7)(-1)=64+28=92>0$
(d) $D=(5)^2-4(2)(5)=25-40=-15<0$
(a) $D=(-10)^2-4(1)(2)=100-8=92>0$
(b) $D=(-12)^2-4(1)(-16)=144+64=208>0$
(c) $D=(8)^2-4(7)(-1)=64+28=92>0$
(d) $D=(5)^2-4(2)(5)=25-40=-15<0$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In the given figure, if $AB = 8\ cm$ and $PE = 3\ cm$, then $AE =$
→In $\triangle\text{ABC},$ $D$ and $E$ are points on side $AB$ and $AC$ respectively such that $DE || BC$ and $AD : DB = 3 : 1$. If $EA = 3.3cm$, then $AC =$
→If $\tan\theta=\frac{\text{a}}{\text{b}}$ then $\frac{(\text{a}\sin\theta-\text{b}\cos\theta)}{(\text{a}\sin\theta+\text{b}\cos\theta)} =?$
→For some integer m, every even integer is of the form:
In the given figure, $QR$ is a common tangent to the given circle, touching externally at the point $T$. The tangent at $T$ meets $QR$ at $P$. If $PT = 3.8cm$ then the length of $QR$ is:
→If common difference of AP is 5 then $a_{18}-a_{13}=$_________
→The angle of elevation of the top of a tower from a point on the ground, which is $30 m$ away from the foot of the tower is $45^{\circ}$. The height of the tower (in metres) is
→The total surface area of a cube is $32 \frac{2}{3} m ^2$. The volume of the cube (in $m ^3$ ) is
→The graph of the equations $5 x-3 y+9=0$ and $10 x-6 y+18=0$ represents .............. lines.
→The LCM and HCF of two non-zero positive numbers are equal, then the numbers must be