Εικόνες σελίδας
PDF
Ηλεκτρ. έκδοση

Therefore, taking the square root of the square of the coefficient of the second term increased by four times the coefficient of the first term into the term independent of x, we get

±√2025+576=±√2601=±51.

This added to the coefficient of the second term with the sign changed, gives

45+51.

which must be divided by twice the coefficient of the first term. Hence,

[blocks in formation]

Either of which values of x, will verify the equation.

[blocks in formation]

This, when reduced to the general form, becomes

Squaring 18, we get

x2-18x=-72.

(18)2=-324.

Four times the first coefficient multiplied into -72,

gives

4x-72-288,

which added to 324, gives 36, the square root of which

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small]

This, cleared of fractions, becomes

3x2-5x=7x+36.

[blocks in formation]

Therefore,

[blocks in formation]

4,or-31

[merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]

can be solved by the above rule, which indeed will agree with the form under consideration in the particular case of n=1.

If, in the above equation, we write y for x", and consequently y2 for x2", it will become

ay2+by=c,

which is precisely of the form of (A), Art. 117. Consequently,

[merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small]

This value of x must hold for all values of the con

stants n, a, b, and c, whether positive or negative, integral or fractional.

EXAMPLES.

1. Given x+ax2=b, to find x.

This becomes y2+ay=b, when for x2 we write y.

[merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

1

3. Given 2(1+x—x2)—√1+x—x2———, to find x.

If, for 1+x—x2, we put y2, our equation will become

[merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]

Resubstituting 1+x-x2, for y2, we have, when we

[blocks in formation]

When we take the other value of y2, we have

[merged small][merged small][ocr errors][merged small][merged small][merged small][subsumed][ocr errors][merged small][subsumed][merged small][merged small][merged small][merged small][ocr errors][ocr errors]

4. Given x1-25x2——144, to find the four values

of x.

Let x2-y, and the above equation will become

[blocks in formation]

Consequently, x=+4, or -4; or else x=+3, or -3.

5. Given 7-8, to find the four values of x.

« ΠροηγούμενηΣυνέχεια »