Question

Montrer que
a²+b²+c²+d²+e²>a(b+c+d+e)

Answer 1

Answer:

a²+b²+c²+d²+e²>a(b+c+d+e)

Put 1

$1 + 1 + 1 + 1 + 1 \: > 1(1 + 1 + 1 + 1) \\ 5 > 4$

Put 2

$5 \times 4 > 2 \times 8 \\ 20 > 16$

Put 3

$5 \times 9 > 3 \times 12 \\ 45 > 36$