Solve system of equation algebraically
y = 2x - 3
x + y = 18

x = 7

y = 11

Step-by-step explanation:

Given the system;

y = 2x - 3

x + y = 18

1. Approach

The easiest way to solve this system of equations is to solve the second equation for the variable (y). Then add the systems, use algebra to solve for the value of (x), then substitute that value back into one of the original equations to solve for the value of (y). Another name for the method in use is the method of elimination, this is when a [erspm manipulates one of the equations in a system of the equation such that when they add the equations, one of the variables eliminatates. Thus, they can solve for the other variable and the backsolve for the value of the unknown variable.

2. Solve one of the equations for a variable

Manipulate the system such that each equation is solved for the same variable,

x + y = 18

Inverse operations,

x + y = 18

-18        -18

x + y - 18 = 0

   -y         -y

x - 18 = -y

3. Use elimination

Now substitute this back into the original system,

y = 2x - 3

-y = x - 18

Add the systems,

y = 2x - 3

-y = x - 18

0 = 3x - 21

Inverse operations,

0 = 3x - 21

+21       +21

21 = 3x

/3    /3

7 = x

4. Find the value of the unknown variable

Backsovle to find the value of (y),

x + y = 18

Substitute,

7 + y = 18

Inverse operations,

7 + y = 18

-7        -7

y = 11

X=3 Y=15

Step-by-step explanation: First you need to use the problem 18/2=x to find the value of x. Now to find the value of y, you need to subtract 3 from 18.  Then you solve

15=2(9)-3 15+3=18

proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles.(more about triangle types) therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.

step-by-step explanation:

an isosceles triangle has two congruent sides and two congruent angles. the congruent angles are called the base angles and the other angle is known as the vertex angle. ∠bac and ∠bca are the base angles of the triangle picture on the left. the vertex angle is ∠abc