Question

what is solution of the pair of equations and x+y= -7​

Answer 1

Step-by-step explanation:

Problem 1. Solve the following pair of equations for and y

2.-=1 Sr +20 = 2

Solution, There are many ways to do this.

We can use substitution. First we solve for y in terms of

Then we substitute in the other equation:

52 + 2y = 2 50 + 2(2r - 1)-2

5 x+4 r-2=2

1

Then we go back to Equation (1) to get y

y- 2r -1

(1) (2)

1

Alternatively, we could use matrix theory: The equations could be writen as

=

Since

it follows that

So r= and y--A

Problem 2. Suppose that there are 40 students in a class made up of sophomores, and juniors, and seniors. There are three times as many juniors as sophomores. The tomber of seniors equals the number of sophomores and juniors combined. How many sophmores, and juniors, and seniors are there?

Sohdion. L a denotes the numbers of sophomores, and juniors, and seniors respen- tively. We have

- 2 +

to +: = 10.

Let us get into reduced echelon form the matrix

1 40 1 1 -1 -3 1 0 0.

I 1 1 40 40 111 40 -3 1 -1 0 - 0 0 -2 -10 0 4 3 120 0 0 110 20 Jo 4 3 120 001 20 1 10 201 100 57

+ 0 40 6O- 00 15 + 0 1 0 15

0 0 I 20

0 01 20

001 20

Answer 2

Step-by-step explanation:

x= 3y + 4z - 5

therefore

y - 1 = z

sin(x-y)= sinxcosy- cosxsinyvalues are 17.42 15.96 21.49 and 17.83 what is the fifth valueQU) Test the convergence or

Test the convergence or divergence of the series: