Factorise: 4x2+9y2+16z2+12xy–24yz–16xz.
We have 4x2+9y2+16z2+12xy–24yz–16xz.
=(2x)2+(3y)2+(−4z)2+2(2x)(3y)–2(3y)(4z)–2(2x)(4z)
=(2x)2+(3y)2+(−4z)2+2(2x)(3y)+2(3y)(−4z)+2(2x)(−4z)
Using identity, (x+y+z)2 = x2+y2+z2+2xy+2yz+2zx
=(2x+3y−4z)2
=(2x+3y−4z)(2x+3y−4z)