Answer:
You have to eliminate one of the variables when the equations are added.
A) x + 2y + z = 10
B) 2x -y +3z = -5
C) 2x -3y -5z = 27
We mulutiply A) by 2 then add it to B and C
A) 2x + 4y + 2z = 20 and the sum =
6x = 42 Luckily, the "y" and "z" variables cancel out and we find:
x = 7
Then we use x =7 in calcucating equation A) and B)
A) 2y + z = 3
B) -y + 3z = -19
THEN solve for y and z by eliminating variables.
Step-by-step explanation:
Answer: A
Step-by-step explanation:
Focus on what it is saying. It is saying that 5x IS LESS THAN OR EQUAL TO 15.
So we are looking for smaller numbers, that is, values of x, in order to make this statement true.
So on a number line we are looking for the left part shaded in.
Furthermore... notice that the sign has "or equal to". Thus the circle is going to be shaded in. The circle is not going to be open and empty. Through this we have eliminated answers B and C.
So the answer is A because— remember— the left side of the number line is shaded. It encompasses negative numbers. A negative number times 5 will definitely be less than 15.
Answer:
44
Step-by-step explanation:
All three series converge, so the answer is D.
The common ratios for each sequence are (I) -1/9, (II) -1/10, and (III) -1/3.
Consider a geometric sequence with the first term <em>a</em> and common ratio |<em>r</em>| < 1. Then the <em>n</em>-th partial sum (the sum of the first <em>n</em> terms) of the sequence is

Multiply both sides by <em>r</em> :

Subtract the latter sum from the first, which eliminates all but the first and last terms:

Solve for
:

Then as gets arbitrarily large, the term
will converge to 0, leaving us with

So the given series converge to
(I) -243/(1 + 1/9) = -2187/10
(II) -1.1/(1 + 1/10) = -1
(III) 27/(1 + 1/3) = 18