✔ 最佳答案
Hi!!
Let's do it:
x² - 5x = 6;
x² - 5x + 6 = 0;
Now we must factorise that expression, x² - 5x - 6. To factor it we should try to divide it using Ruffini's method with the divisors of the independent term, 6.
6 = 2 ∙ 3.
The divisors are 1, -1, 2, -2, 3, -3, 6 and -6.
Let's divide it by x - 1.
(x² - 5x - 6)/(x - 1)
It isn't a exact division. 1 isn't a root.
Let's divide it by x + 1.
(x² - 5x - 6)/(x + 1) = (x - 6)
It IS a exact division. -1 and 6 are roots.
Therefore the factored form is:
x² - 5x - 6 = (x - 6)(x + 1)
We can now reinsert it into the equation:
(x - 6)(x + 1) = 0;
x - 6 = 0, x = 6
x + 1 = 0; x = -1
∴ x = 6 and x = -1
Well, bye hope it helped, Happy Xmas :D!!