Given that x^2+10x+3 can be written in the form (x+a)^2+b, find the values of a and b.

We can tackle this question by completing the square. Completing the square allows us to write a quadratic equation (x^2+10x+3) in the simpler form (x+a)^2+b.To complete the square, first we need to find the value of our a. To find the value of our a we need to halve the x term coefficient (halve the number in front of the x). In this question, the number in front of our x is 10 so our a value must be 5.We can then substitute this value of a into our completing the square equation: (x+5)^2+b.To find our b value we need to expand out (x+5)^2 + b and compare this to our original equation.If we expand (x+5)^2 + b we get x^2 + 10x + 25 + b. However, looking at our original equation we know our x^2 and x terms are correct but the constant (the term with no x's) we should be left with is 3 but instead we are left with 25 + b. Hence, 25 + b = 3 (as these are the only terms without x's) so b = -22.Thus, we can write the equation x^2+10x+3 as (x+5)^2 -22 so a = 5 and b = - 22.

KC
Answered by Katie C. Maths tutor

9683 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Find x: 4x + 7 = 27


Ed has 4 cards. There is a number on each card. Three of the numbers are 12, 6 and 15. The mean of the numbers is 10. What is the fourth number?


How do you solve simultaneous equation where one of them involves powers?


We are given a right angled triangle with one side of unknown length. The shortest side is 3cm long, and the longest side is 5cm long. Calculate the remaining side.


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