Ex. 14. Given x2+15x=35x-3x2, to find the value of x.

Here 12 is the least common multiple of 6, 4, 3, and 2 ; multiplying both sides of the equation by 12, 2x-3x+120=4x-6x+132,;

by transposition, 2x-3x-4x+6x=132-120,

or 8x-7x=12;

..x=12.

of x.

:: 7:4, to find the value Ans. x=2.

of x.

Ex. 28. Given (2x+8)=4x+14x+172, to find the value

Ans. x=6.

of x.

Ans. x=12.

Ex. 33. Given 5ax-2b+4bx=2x+5c, to find the value

of x.

Ans. x=.

5c+2b 5a+46-2

e g

a

C

Ex. 55. Given + + + k, to find the value of x.

bx dx fx hx

Ans. x=

adfh+bcfh+bdeh+bdfg bdjhk

a2c

Ex. 56. Given (a+x).(b+x)—a.(b+c)==+x2, to find

b

CHAPTER IV.

ON

SIMPLE EQUATIONS,

INVOLVING TWO OR MORE UNKNOWN QUANTITIES.

202. It has been observed (Art. 184), that an equation was the translation into algebraic language of two equivalent phrases comprised in the enunciation of a question; but this question may comprehend in it a greater number, and if they are well distinguished two by two, and independent of one another, they furnish a certain number of equations.

Thus, for example, let us propose to find two numbers, such that double the first added to the second, gives 24, and that five times the first, plus three times the second, make 65. We find here two phrases, which express the same thing in different terms; 1st, the double of an unknown number, plus another unknown number, then the equivalent 24; 2d, five times the first unknown number, plus three times the second, then the equivalent 65.

The translation is easy, and it gives these two determinate equations

2x+y=24; 5x+3y=65.

When two or more equations, involving as many unknown quantities, are independent of one another, they are called determinate. But if for the second of these two conditions we had substituted this and such that six times the first number, plus three times the second, make 72; these two phrases express nothing more than the first two, since that we have only tripled two equal results; we should have but one translation, and consequently a single equation. It can therefore happen that we may have less equations than unknown quantities, and then the question is said to be indeterminate; because the number of conditions would be insufficient for the

determination of the unknown quantities, as we shall see clearly illustrated in the following section.