Math Problem Statement

Find the point of intersection of the two straight lines in each of the following cases: a) y = 2x - 1 and y = 3 - x, b) x + y - 16 = 0 and x + 2y = 10, c) 2y = x + 5 and y = -2x, d) 3y = 6 - 4x and 6y = x - 12.

Solution

Let's solve the given problems one by one to find the point of intersection of each pair of lines.

Problem a:

Equations:

  1. y=2x1y = 2x - 1
  2. y=3xy = 3 - x

To find the point of intersection, we set the two equations equal to each other:

2x1=3x2x - 1 = 3 - x

Solve for xx:

2x+x=3+1    3x=4    x=432x + x = 3 + 1 \implies 3x = 4 \implies x = \frac{4}{3}

Substitute x=43x = \frac{4}{3} into one of the equations to find yy. Let's use y=2x1y = 2x - 1:

y=2(43)1=831=8333=53y = 2 \left( \frac{4}{3} \right) - 1 = \frac{8}{3} - 1 = \frac{8}{3} - \frac{3}{3} = \frac{5}{3}

So, the point of intersection is:

(43,53)\left( \frac{4}{3}, \frac{5}{3} \right)

Problem b:

Equations:

  1. x+y16=0    y=16xx + y - 16 = 0 \implies y = 16 - x
  2. x+2y=10x + 2y = 10

Substitute y=16xy = 16 - x into the second equation:

x+2(16x)=10x + 2(16 - x) = 10

Simplify and solve for xx:

x+322x=10    x=22    x=22x + 32 - 2x = 10 \implies -x = -22 \implies x = 22

Substitute x=22x = 22 back into the first equation to find yy:

y=1622=6y = 16 - 22 = -6

So, the point of intersection is:

(22,6)(22, -6)

Problem c:

Equations:

  1. 2y=x+5    x=2y52y = x + 5 \implies x = 2y - 5
  2. y=2xy = -2x

Substitute x=2y5x = 2y - 5 into the second equation:

y=2(2y5)y = -2(2y - 5)

Solve for yy:

y=4y+10    5y=10    y=2y = -4y + 10 \implies 5y = 10 \implies y = 2

Substitute y=2y = 2 back into x=2y5x = 2y - 5:

x=2(2)5=45=1x = 2(2) - 5 = 4 - 5 = -1

So, the point of intersection is:

(1,2)(-1, 2)

Problem d:

Equations:

  1. 3y=64x    y=24x33y = 6 - 4x \implies y = 2 - \frac{4x}{3}
  2. 6y=x12    y=x626y = x - 12 \implies y = \frac{x}{6} - 2

Set the two expressions for yy equal to each other:

24x3=x622 - \frac{4x}{3} = \frac{x}{6} - 2

Multiply every term by 6 to clear the fractions:

6(24x3)=6(x62)6 \cdot \left( 2 - \frac{4x}{3} \right) = 6 \cdot \left( \frac{x}{6} - 2 \right)

Simplify:

128x=x1212 - 8x = x - 12

Combine like terms:

12+12=x+8x    24=9x    x=249=8312 + 12 = x + 8x \implies 24 = 9x \implies x = \frac{24}{9} = \frac{8}{3}

Substitute x=83x = \frac{8}{3} back into y=x62y = \frac{x}{6} - 2:

y=8/362=8182=492=49189=149y = \frac{8/3}{6} - 2 = \frac{8}{18} - 2 = \frac{4}{9} - 2 = \frac{4}{9} - \frac{18}{9} = -\frac{14}{9}

So, the point of intersection is:

(83,149)\left( \frac{8}{3}, -\frac{14}{9} \right)

Would you like further details on any of the steps? Here are some related questions:

  1. How do you find the intersection of lines graphically?
  2. What are some applications of finding line intersections in real life?
  3. What methods can be used to solve linear systems of equations?
  4. Can two lines intersect more than once in Euclidean geometry?
  5. How do parallel and perpendicular lines affect the intersection points?

Tip: When solving equations, always double-check each substitution step to ensure accuracy.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
System of Equations

Formulas

y = mx + b (Slope-intercept form)
Substitution method for solving systems of equations

Theorems

Fundamental Theorem of Algebra (applied to systems of equations)

Suitable Grade Level

Grades 9-12