Does the equation: x^2+5x-6 have two real roots? If so what are they?

Having two real roots is equivalent to having two intersections with the x axis.

The equation is a parabola (a U shape) so, having two real roots is equivalent to having the lowest point of the curve below the x axis.

By differentiation we have that 2x+5 is the rate of change, and setting this equal to zero gives the stationary point x=-5/2.

Using the equation we then have:

y=(-5/2)2+5(-5/2)-6=-12.25

This shows that the minimum point of the curve is (-5/2,-12.25) which is below the x axis.

Thus, there are two real roots and applying the quadratic formula gives the values: -6 and 1.

Where the quadratic formula is:

[-b+sqrt(b2-4ac)] / [2a] and [-b-sqrt(b2-4ac)] / [2a]

SB
Answered by Stephen B. Maths tutor

5294 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Complete the square for the following equation: 2x^2+6x-3=0


Differentiate sin(2x)/x^2 w.r.t. x


Use Simpson's rule with 5 ordinates (4 strips) to find an approximation to "integral between 1 and 3 of" 1/sqrt(1+x^3) dx giving your answer to three significant figures.


solve x^3+2x^2+x=0


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning