First slide

Theory of expressions

Question

If x is real, then the value of $x^{2} - 6 x + 13$ will not be less than

Moderate

A

4
B

6
C

7
D

8

Solution

Let $y = x^{2} - 6 x + 13 \Rightarrow x^{2} - 6 x + 13 - y = 0$
Its discriminant $D \geq 0 \Rightarrow 36 - 4 (13 - y) \geq 0$
$\Rightarrow 36 - 52 + 4 y \geq 0 \Rightarrow 4 y \geq 16 \Rightarrow y \geq 4$
Hence y is not less than 4.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App