Factorise:4x2+9y2+25z2+12xy+30yz+20zx
Now,
4x2+9y2+25z2+12xy+30yz+20zx
Using identity (a+b+c)2=a2+b2+c2+2ab+2bc+2ac
=(2x)2+(3y)2+(5z)2+2×2x×3y+2×3y×5z+2×2x×5z
=(2x+3y+5z)2
∴4x2+9y2+25z2+12xy+30yz+20zx=(2x+3y+5z)(2x+3y+5z)
Factorise: 4x2+9y2+16z2+12xy–24yz–16xz.