Find the minimum value of the quadratic 3x^2-8x+1.

This is a question about completing the square. The first step involves taking the factor of 3 our of the expression to reach the correct form for completing the square to reach 3(x^2-(8/3)x)+1. Then, consider x^2-(8/3)x and complete the square of this expression. The coefficient of x is -(8/3) so half of that is -(4/3) so we get (x-(4/3))^2-(16/9). We now substitute this back into the expression before so we have 3x^2-8x+1=3(x^2-(8/3)x)+1=3((x-(4/3))^2-(16/9))+1=3(x-(4/3))^2-(16/3)+1=3(x-(4/3))^2-(13/3)and this is in the correct form for completing the square. To find the minimum value we simply have to notice that the smallest value the squared term can be is 0 so the minimum value of the whole expression is -(13/3).

JM
Answered by Jamie M. Maths tutor

3390 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How many solutions does a quadratic equation have?


Make x the subject of the following formula: 5(3x -2y) = 14 - 2ax


There are 10 boys and 20 girls in a class. In a class test, the mean score of the boys is 77. The mean score of the girls is 80. What is the mean score of the whole class?


5 tins of soup have a total weight of 1750 grams. 4 tins of soup and 3 packets of soup have a total weight of 1490 grams. Work out the total weight of 3 tins of soup and 2 packets of soup.


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