The equations 4 x minus 5 y = 5, 3 x + 10 y = 20, 4 x minus 5 y = negative 5, and 3 x + 10 y = negative 20 are shown on the grap
h below. On a coordinate plane, there are 4 lines. Green line goes through (0, 1) and (2.5, 3). Orange line goes through (0, negative 1) and (2.5, 1). Blue line goes through (0, 2) and (3.5, 1). Pink line goes through (0, negative 2) and (3.5, negative 3). Which system of equations has a solution of approximately (–2.7, –1.2)? 4 x minus 5 y = negative 5 and 3 x + 10 y = negative 20 4 x minus 5 y = 5 and 3 x + 10 y = 20 4 x minus 5 y = 5 and 3 x + 10 y = negative 20 4 x minus 5 y = negative 5 and 3 x + 10 y = 20
2 answers:
Answer:
4 x minus 5 y = negative 5 and 3 x + 10 y = negative 20
Step-by-step explanation:
The equations
4 x - 5 y = 5 (red)
3 x + 10 y = 20 (blue)
4 x - 5 y = -5 (green)
3 x + 10 y = -20 (purple)
are shown in the picture attached. As we can see there, the point (–2.7, –1.2) is on the intersection of the purple and green lines. Therefore is the solution of the system:
4 x - 5 y = -5
3 x + 10 y = -20
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The Equation of a Line
The slope-intercept form of a line can be written as:
y = mx + b
Where m is the slope of the graph of the line and b is the y-intercept.
In the specific case where the line passes through the origin (0,0), we can find the value of b by substituting x=0 and y=0:
0 = m(0) + b
Solving for b:
b = 0.
Thus, the equation of the line reduces to:
y = mx
We only need to find the value of the slope.
That is where we need the second data. Our line is perpendicular to the line of equation 4x + 3y = 6.
Solving for y:
The slope of the second line is -4/3.
We must recall that if two lines of slopes m1 and m2 are perpendicular, then:
Substituting the value of m1 and solving for m2:
The slope of our line is 3/4 and the required equation is:
From this last equation, we need to find the general form of the line.
Multiply both sides of the equation by 4:
4y = 3x
Subtract 3x on both sides:
4y - 3x = 0
Reorder:
-3x + 4y = 0