How do you complete the square?

Completing the square is often useful when solving equations! An example: x+6x-7=0. Step 1) We want to move the constant to the right hand side: x2+6x=7. Step 2) Now, add the square of the coefficient of x on to both sides: x2+6x+32=7+32 -> x2+6x+9=16. Step 3) Factorise the left hand side: (x+3)2=16. Step 4) Square root the equation and solve: x+3=+/-4  -> x=-3+/-4.

LW
Answered by Lisa W. Maths tutor

3773 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How do I differentiate y = ln(sin(3x))?


Differentiate x^x


A circle with centre C has equation x^2+8x+y^2-12y=12. The points P and Q lie on the circle. The origin is the midpoint of the chord PQ. Show that PQ has length nsqrt(3) , where n is an integer.


The quadratic equation (k+1)x^2+12x+(k-4)=0 has real roots. (a) Show that k^2-3k-40<=0. (b) Hence find the possible values of k.


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences