x^2-16=0 please help solve?
回答 (3)
2010-03-15 2:28 pm
✔ 最佳答案
a^2 - b^2 ≡ (a + b)(a - b)x^2 - 16 = 0
x^2 - 4^2 = 0
(x + 4)(x - 4) = 0
x + 4 = 0
x = -4
x - 4 = 0
x = 4
∴ x = -4, 4
2010-03-15 1:48 pm
You can do the same thing to both sides, to get the answer.
First, add 16 to both sides.
x^2 - 16 + 16 = 0 + 16
x^2 +0 = +16
x^2 = 16
Then, take the square root of both sides.
Remember, the square root of a number is TWO numbers.
The square root of 4, for example, is +2 and -2.
First, add 16 to both sides.
x^2 - 16 + 16 = 0 + 16
x^2 +0 = +16
x^2 = 16
Then, take the square root of both sides.
Remember, the square root of a number is TWO numbers.
The square root of 4, for example, is +2 and -2.
2010-03-15 1:47 pm
There are 2 answers, x=4 and x=-4
x^2-16=0
so x^2=16
so x=+/- 4
x^2-16=0
so x^2=16
so x=+/- 4
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