Question

4 bit : Expand , 5 bit : Factorise

Answer 1

$25x {}^{2} + 16y { }^{2} + 4z {}^{2} - 40xy + 16yz - 20zx \\ \\ (5x) {}^{2} + (4y) {}^{2} + (2z) {}^{2} - 2 \times 5x \times 4y + 2 \times 4y \times 2z - 2 \times 5x \times 2z \\ \\ (5x - 4y - 2z) (5x - 4y - 2z)$