The correct option is A 9x2+16y2+25z2+24xy+40yz+30xz
We know that (a+b+c)2=a2+b2+c2+2ab+2bc+2ac.
Here, a=3x,b=4y and c=5z.
On substituting these values in he known identity, we get,
(3x+4y+5z)2=(3x)2+(4y)2+(5z)2+2(3x)(4y)+2(4y)(5z)+2(3x)(5z)=9x2+16y2+25z2+24xy+40yz+30xz