Work out the integer values that satisfy: x^2−7 x+ 11<0

It's easier if we first visualise the function on a graph, then we can see in which regions it is negative. From there we can see which integer values lie in this region. A positive quadratic function has the shape of a U, and remember a negative quadratic function has the shape of an n. To sketch the graph you will want to find the roots of the function, to see where the curve crosses the x axis. Solve f(x)=0. Does it factorise? no. Use quadratic formula: x = (7+-sqrt(49-44))/2 . Sketch the U curve making it cross the x axis at these 2 values. (go to whiteboard) Observe for what values of x are the y values negative (curve below the x axis). You should find that between the two roots the graph is negative ( the bottom of the U). Therefore the integer values we are looking for are those lying between 2.38 and 4.61, i.e. 3,4.
You should now check the values 2,3,4,5 and check that 2 and 5 are positive, while 3 and 4 are negative. An alternative is that when you know roughly what the roots are, you can start guessing integers that might be positive and negative and work it out that way. After doing a few of these questions, you can speed up the process: solve for roots. what are the integers between the roots? But make sure you understand why this works.

JP
Answered by Jamie P. Maths tutor

8186 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve the following equation: 7x + 6 = -5x - 42


There are 12 counters in a box, 5 red and 7 blue. 2 counters are taken out at random without replacement, what is the probability that they are the same colour?


Increase 32 million by 4%. Give your answer correct to the nearest million.


(a)Show that the lines y=3x+7 and 2y–6x=8 are parallel. [3 marks] (b) Is the point (–5, –6) above, below or on the line y = 3x + 7 ? Do not use a graphical method. [2 marks] [Total 5 marks]


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:

© 2026 by IXL Learning