Math Problem Statement

answer with complete solution

Solve the following problems. Find the equation of the line whose x-intercept is 8 and y-intercept is -1, and other related linear algebra questions.

Solution

Let's go through these one by one, solving each of the problems step by step.

1. Find the equation of the line whose x-intercept is 8 and y-intercept is -1.

The equation of a line in intercept form is: xa+yb=1\frac{x}{a} + \frac{y}{b} = 1 where aa is the x-intercept and bb is the y-intercept.

Given:

  • a=8a = 8
  • b=1b = -1

Substitute into the formula: x8+y1=1\frac{x}{8} + \frac{y}{-1} = 1 Simplify the equation: x8y=1\frac{x}{8} - y = 1 Multiply through by 8 to eliminate the fractions: x8y=8x - 8y = 8 Thus, the equation of the line is: x8y=8x - 8y = 8

2. Reduce 3x8y+24=03x - 8y + 24 = 0 to the intercept form.

We start with the given equation: 3x8y+24=03x - 8y + 24 = 0 Move the constant term to the other side: 3x8y=243x - 8y = -24 Now, divide through by 24-24 to rewrite in intercept form: 3x24+8y24=1\frac{3x}{-24} + \frac{-8y}{-24} = 1 Simplify: x8+y3=1\frac{x}{-8} + \frac{y}{3} = 1 Thus, the intercept form is: x8+y3=1\frac{x}{-8} + \frac{y}{3} = 1

3. Reduce x+6y7=0x + 6y - 7 = 0 to the normal form. Give the distance of the line from the origin.

The normal form of a line is written as: Ax+By+C=0Ax + By + C = 0 with A2+B2=1A^2 + B^2 = 1. We first reduce the equation to normal form.

Given: x+6y7=0x + 6y - 7 = 0 Move the constant to the other side: x+6y=7x + 6y = 7 Now, divide through by the square root of the sum of squares of the coefficients of xx and yy to normalize: A=1,B=6    A2+B2=12+62=1+36=37A = 1, B = 6 \implies \sqrt{A^2 + B^2} = \sqrt{1^2 + 6^2} = \sqrt{1 + 36} = \sqrt{37} Divide by 37\sqrt{37}: x37+6y37=737\frac{x}{\sqrt{37}} + \frac{6y}{\sqrt{37}} = \frac{7}{\sqrt{37}} Thus, the normal form is: x37+6y37=737\frac{x}{\sqrt{37}} + \frac{6y}{\sqrt{37}} = \frac{7}{\sqrt{37}}

The distance from the origin to the line is given by: d=CA2+B2=737=737d = \frac{|C|}{\sqrt{A^2 + B^2}} = \frac{|7|}{\sqrt{37}} = \frac{7}{\sqrt{37}}

4. What is the equation of a line through (5, 2) with the x-intercept thrice the y-intercept?

Let the x-intercept be 3b3b and the y-intercept be bb. The equation of the line in intercept form is: x3b+yb=1\frac{x}{3b} + \frac{y}{b} = 1 Multiply through by bb to simplify: x3+y=b\frac{x}{3} + y = b Substitute the point (5,2)(5, 2) into the equation: 53+2=b\frac{5}{3} + 2 = b Simplify: 53+63=b    b=113\frac{5}{3} + \frac{6}{3} = b \implies b = \frac{11}{3} Now substitute b=113b = \frac{11}{3} into the original equation: x3+y=113\frac{x}{3} + y = \frac{11}{3} Multiply through by 3: x+3y=11x + 3y = 11 Thus, the equation of the line is: x+3y=11x + 3y = 11

5. Find the equation of a line through (4,2)(-4, -2) and forming with the coordinate axes a triangle with area 16.

The area of a triangle formed by a line with the x- and y-intercepts is given by: Area=12×x-intercept×y-intercept\text{Area} = \frac{1}{2} \times |x\text{-intercept}| \times |y\text{-intercept}| Let the x-intercept be aa and the y-intercept be bb. The equation of the line in intercept form is: xa+yb=1\frac{x}{a} + \frac{y}{b} = 1 The area is given as 16, so: 12×a×b=16\frac{1}{2} \times |a| \times |b| = 16 a×b=32|a| \times |b| = 32 Also, the line passes through the point (4,2)(-4, -2), so substituting into the

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Intercept Form of Line
Normal Form of Line
Geometry
Distance from Origin

Formulas

Intercept form of line: (x/a) + (y/b) = 1
General form of line: Ax + By + C = 0
Distance from origin: |C| / sqrt(A^2 + B^2)
Area of triangle: 1/2 * |x-intercept| * |y-intercept|

Theorems

Distance formula
Equation of a line through two points
Triangle area formula

Suitable Grade Level

Grades 9-12