Respuesta :
Question: x² - 8x = 3
First we factorise the x²-8x like so: (remember, you halve the 8 to get 4)
x² - 8x = 3
(x - 4)² - 16 = 3 .
(x - 4)² = 19
x - 4 = √19
x = 4±√19
Answer:
x = 4±√19
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Some explanations:
in: (x - 4)² - 16 = 3
we have to subtract 16.
If we didn't, then (x - 4)² would expand to x² - 8x + 16
We don't want this since x² - 8x + 16 is not the same as x² - 8x, so we have to subtract 16 to make it the same:
x² - 8x = (x - 4)² - 16 but x² - 8x [tex]\neq[/tex] (x - 4)²
