A total price can be produced by many different item combinations. Additional information, such as the total number of items, narrows those possibilities. A linear equation system writes each piece of information as an equation. Its solution must satisfy every equation at once.
A system may contain any number of equations. To determine unique values for x,y,z, however, the equations must provide three independent constraints. A common square form is:
In the substitution method, express one variable in terms of another, then insert that expression into the other equation. The following example shows each step.
{2x+3y=21x+y=10…(1)…(2)
Step1: Express one variable from the simpler equation.
From equation (2): x+y=10, we express x in terms of y:
x=10−y…(3)
Step2: Substitute into the other equation.
Insert equation (3) into equation (1):
2(10−y)+3y=21
Step3: Solve the resulting equation.
20−2y+3y=21
20+y=21
y=1…(4)
Step4: Substitute the calculated value to find the other variable.
Substitute the value y=1 from equation (4) into equation (3):
In basketball, there are three types of shots with different point values: free throws (1 point), two-point shots (2 points), and three-point shots (3 points).
Define:
a = number of 1-point shots
b = number of 2-point shots
c = number of 3-point shots
If Wijaya scored 27 points, made 16 shots total with 6 of them being free throws, then:
Linear equation systems have three possible solution types:
Exactly one solution: When the lines intersect at a single point (or planes intersect at a single point)
No solution: When the lines are parallel (or planes do not intersect)
Infinitely many solutions: When the lines coincide (or planes intersect along a line or plane)
In three dimensions, one linear equation represents a plane. Two distinct nonparallel planes intersect in a line. For three or more planes, the common solution set may be a point, a line, a plane, or empty.
Linear Equation System with Infinitely Many Solutions
The second equation is 2 times the first, so both graphs coincide and appear as one line. The line for the first equation is drawn wider so both equations remain visible along the same path.