Question

(x+1)(x+2)(x+3)(x+4) = 99 (by hand)

Answer 1

\[t=x^2+5x\]

Answer 2

that was pure genius !

Answer 3

ty :)

Answer 4

Enlighten me....

Answer 5

Or better, tell me what t is?

Answer 6

(x+1)(x+4)(x+2)(x+3) = 99
(x^2 + 5x +4)(x^2 + 5x + 6) = 99
=> (x^2 + 5x)^2 + 10 (x^2 + 5x) + 75 = 0

easier after that..

Answer 7

(x^2 + 5x +4)(x^2 + 5x + 6) = 99

(y-1)(y+1) = 99

Answer 8

aha,,cool !

Answer 9

ya much simpler :)

Answer 10

Yours is also a timesaver:-)

Answer 11

It will work whenever there is a sequence (arithmetic) or some symmetry (like 1,5,7,11)