# Math Help - quadratic form

construct the quadratic form of a11x1^2+a12x1x2+a13x1x3+a23x2x3+a33x3^2

2. Originally Posted by elenkgr
construct the quadratic form of a11x1^2+a12x1x2+a13x1x3+a23x2x3+a33x3^2

the above will yield a quadratic form of three variables. the quadratic form of the above is:

a11x1^2 + 0x2^2 + a33x3^2 + a12x1x2 + a13x1x3 + a23x2x3

i included x2^2 even though its coeffcient is zero, i don't think you need to do this, i just like being thorough.