Answer:
The point at which these lines intersect is (-0.50, 1.07). We can solve this in two ways: mathematically or graphically. Both are described.
Explanation:
We have 2 equations, so we'll assume that the question is to find if they intersect, and if they do, where is the point of intersection.
Let's rewite the equations in slope-intercept format of y=mx+b, where m is the slope and b is the y-intercept (the value of y when x=0).
1) 9x + 7y = 3
7y = -9x + 3
y = -(9/7)x + (3/7) This line has a slope of -(9/7) and a y-intercept of +(3/7).
2) x - 7y=-8
-7y = -x - 8
y = (1/7)x + (8/7) This line has a slope of (1/7) and an intercept of (8/7)
The line have different slopes, so they will intersect. We can find the intersection point by either graphing or by substitution. We'll do both:
Substitution
We'll rearrange one equation in terms of x and then use that value of x in the second equation. Thuis has the effect of eliminating one of the variables (x or y) so that we can solve for the remaining value of x or y,
We've rearranged both equations so that they have y equal to an expression involving x. If the lines intersect, we know that y in both equations will be the same at that point, so set the equations equal to each other and solve for x:
y = -(9/7)x + (3/7)
y = (1/7)x + (8/7)
Therefore: -(9/7)x + (3/7) = (1/7)x + (8/7)
-(9/7)x -(1/7)x = + (8/7) - (3/7)
-(10/7)x = +(5/7)
x = (5/7)*(-7/10)
x = (-35/70)
x = -0.50
Now we can use this value of x to find y:
9x + 7y = 3
9(-0.50) + 7y = 3
-4.5 + 7y = 3
7y = 3+4.5
y = (7.5/7)
y = 1.07
The point at which these lines intersect is (-0.50, 1.07)
Graphing:
We can also graph the two equations and then look for the intersection. See the attached graph. The lines intersect at (-0.50, 1.07)
The mathematical approach has more certainty, since it does not require interpreting the intersection point on a graph. Use the graphing approach to check the conclusion from the substitution approach.