Math Problem Statement

Solve the following problems: 1. x^2 - 5x = -6 2. x^2 - x - 6 = 0 3. (x + 2)(x - 5) = 0 4. A rectangular plot of area 36 m² has length (2x + 1) and breadth x. Find the total wire length needed for fencing with three strands. 5. Solve the equation 2x² + 5x - 7 = 0.

Solution

Let's solve these problems step by step:


01. x25x=6x^2 - 5x = -6

Rewriting the equation in standard quadratic form:
x25x+6=0x^2 - 5x + 6 = 0
Factorize the quadratic:
x25x+6=(x2)(x3)=0x^2 - 5x + 6 = (x - 2)(x - 3) = 0
Using the zero-product property:
x2=0orx3=0x - 2 = 0 \quad \text{or} \quad x - 3 = 0
Thus:
x=2orx=3x = 2 \quad \text{or} \quad x = 3


02. x2x6=0x^2 - x - 6 = 0

This is already in standard quadratic form. Factorize:
x2x6=(x3)(x+2)=0x^2 - x - 6 = (x - 3)(x + 2) = 0
Using the zero-product property:
x3=0orx+2=0x - 3 = 0 \quad \text{or} \quad x + 2 = 0
Thus:
x=3orx=2x = 3 \quad \text{or} \quad x = -2


03. (x+2)(x5)=0(x + 2)(x - 5) = 0

Using the zero-product property directly:
x+2=0orx5=0x + 2 = 0 \quad \text{or} \quad x - 5 = 0
Thus:
x=2orx=5x = -2 \quad \text{or} \quad x = 5


04. Rectangular Plot Problem

We are given:

  • Length = 2x+12x + 1
  • Breadth = xx
  • Area = 36m236 \, \text{m}^2

From the area formula (Area=Length×Breadth\text{Area} = \text{Length} \times \text{Breadth}):
(2x+1)x=36(2x + 1) \cdot x = 36
Simplify:
2x2+x=362x^2 + x = 36
Rearrange into standard quadratic form:
2x2+x36=02x^2 + x - 36 = 0
Solve this quadratic using the quadratic formula x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=2a = 2, b=1b = 1, c=36c = -36:
x=1±124(2)(36)2(2)x = \frac{-1 \pm \sqrt{1^2 - 4(2)(-36)}}{2(2)}
x=1±1+2884x = \frac{-1 \pm \sqrt{1 + 288}}{4}
x=1±2894x = \frac{-1 \pm \sqrt{289}}{4}
x=1±174x = \frac{-1 \pm 17}{4}
Solve for both cases:

  1. x=1+174=164=4x = \frac{-1 + 17}{4} = \frac{16}{4} = 4
  2. x=1174=184=4.5x = \frac{-1 - 17}{4} = \frac{-18}{4} = -4.5

Since xx must be positive (it represents length):
x=4x = 4

Now, calculate the length (2x+12x + 1) and breadth (xx):

  • Length: 2(4)+1=9m2(4) + 1 = 9 \, \text{m}
  • Breadth: x=4mx = 4 \, \text{m}

The perimeter of the rectangle is:
P=2(Length+Breadth)=2(9+4)=2(13)=26mP = 2(\text{Length} + \text{Breadth}) = 2(9 + 4) = 2(13) = 26 \, \text{m}

If three strands of wire are required, the total length of wire is:
3×26=78m3 \times 26 = 78 \, \text{m}


05. 2x2+5x7=02x^2 + 5x - 7 = 0

Solve using the quadratic formula:
x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
Here, a=2a = 2, b=5b = 5, c=7c = -7:
x=5±524(2)(7)2(2)x = \frac{-5 \pm \sqrt{5^2 - 4(2)(-7)}}{2(2)}
x=5±25+564x = \frac{-5 \pm \sqrt{25 + 56}}{4}
x=5±814x = \frac{-5 \pm \sqrt{81}}{4}
x=5±94x = \frac{-5 \pm 9}{4}

Solve for both cases:

  1. x=5+94=44=1x = \frac{-5 + 9}{4} = \frac{4}{4} = 1
  2. x=594=144=3.5x = \frac{-5 - 9}{4} = \frac{-14}{4} = -3.5

Thus:
x=1orx=3.5x = 1 \quad \text{or} \quad x = -3.5


Summary of Solutions:

  1. x=2,3x = 2, 3
  2. x=3,2x = 3, -2
  3. x=2,5x = -2, 5
  4. Total wire length = 78m78 \, \text{m}
  5. x=1,3.5x = 1, -3.5

Do you want further explanation or clarification on any part?

Related Questions:

  1. How do you derive the quadratic formula?
  2. What is the discriminant, and how does it determine the nature of roots?
  3. How do you calculate the perimeter of any polygon?
  4. Can you explain why negative lengths are not physically valid in geometry?
  5. What are the steps to factorize a quadratic equation?

Tip: Always rewrite equations into standard quadratic form (ax2+bx+c=0ax^2 + bx + c = 0) before attempting to solve them!

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Factoring
Perimeter Calculation
Area of Rectangles

Formulas

Standard Quadratic Form: ax^2 + bx + c = 0
Quadratic Formula: x = [-b ± sqrt(b² - 4ac)] / 2a
Area of Rectangle: Length × Breadth
Perimeter of Rectangle: 2(Length + Breadth)

Theorems

Zero Product Property
Quadratic Formula

Suitable Grade Level

Grades 8-10