SOLVING TRINOMIALS WITH LEADING COEFFICIENT NOT EQUAL TO 1

The polynomial which is in the form of ax2 + bx + c is known as quadratic polynomial. Here b or c may be 0 some times.

There are two types,

  • Quadratic polynomial with leading coefficient 1.
  • Quadratic polynomial with leading coefficients not equal to 1.

Types of Solving Quadratic Equation

To solve quadratic equation, we follow different ways.

i) Using factoring

ii) Using quadratic formula

iii) Completing the square

iv) Using square root property

Problem 1 :

4x2 - 9 = 0

Solution:

4x2 - 9 = 0

4x2 = 9

x2 = 9/4

x = ± 3/2

So, the solutions are {3/2, -3/2}. 

Problem 2 :

2x2 + 4x + 1 = 0

Solution:

Comparing 2x2 + 4x + 1 = 0 and ax2 + bx + c = 0, we get

a = 2, b = 4 and c = 1

By using quadratic formula,

x = -b±b2-4ac2ax = -4±(4)2-4(2)(1)2(2)x = -4±16-84x=-4±84x = -4±224x=2-2±24x=-2±22x =-2+22 or x=-2-22

Problem 3 :

3x2 - x - 1 = 0

Solution:

Comparing 3x2 - x - 1 = 0 and ax+ bx + c = 0, we get

a = 3, b = -1 and c = -1

By using quadratic formula,

x = -b±b2-4ac2ax = -(-1)±(-1)2-4(3)(-1)2(3)x = 1±1+126x=1±136x =1+136 or x=1-136

Problem 4 :

2x2 - 5x + 1 = 0

Solution:

Comparing 2x2 - 5x + 1 = 0 and ax2 + bx + c = 0, we get

a = 2, b = -5 and c = 1

By using quadratic formula,

x = -b±b2-4ac2ax = -(-5)±(-5)2-4(2)(1)2(2)x = 5±25-84x=5±174x =5+174 or x=5-174

Problem 5 :

2x2 + 6x + 4 = 0

Solution:

2x2 + 6x + 4 = 0

2x2 + 4x + 2x + 4 = 0

2x(x + 2) + 2(x + 2) = 0

(x + 2) (2x + 2) = 0

Equating each factor to 0, we get

x + 2 = 0 and 2x + 2 = 0

x = -1 or x = -2

So, the solutions are x = -1 or x = -2.

Problem 6 :

3x2 + 15x + 18 = 0

Solution:

3x2 + 15x + 18 = 0

3x2 + 6x + 9x + 18 = 0

3x(x + 2) + 9(x + 2) = 0

(x + 2)(3x + 9) = 0

Equating each factor to zero, we get

x + 2 = 0 and 3x + 9 = 0

x = -2 and 3x = -9

x = -3

So, the solutions are x = -3 or x = -2.

Problem 7 :

2x2 - 6x - 8 = 0

Solution:

2x2 - 6x - 8 = 0

2(x2 - 3x - 4) = 0

2(x2 + x - 4x - 4) = 0

2(x(x + 1) - 4(x + 1)) = 0

2(x - 4) (x + 1) = 0

x - 4 = 0 or x + 1 = 0

x = 4 or x = -1

So, the solutions are x = 4 or x = -1.

Problem 8 :

x2 = 6x + 27

Solution:

x2 - 6x - 27 = 0

x2 - 9x + 3x - 27 = 0

x(x - 9) + 3(x - 9) = 0

(x + 3) (x - 9) = 0

x + 3 = 0 or x - 9 = 0

x = -3 or x = 9

So, the solutions are x = -3 or x = 9.

Problem 9 :

x2 = 13x - 36 

Solution:

x2 - 13x + 36 = 0

x2 - 9x - 4x + 36 = 0

x(x - 9) - 4(x - 9) = 0

(x - 4) (x - 9) = 0

x - 4 = 0 or x - 9 = 0

x = 4 or x = 9

So, the solutions are x = 4 or x = 9.

Problem 10 :

2x2 - 5x = 12

Solution:

2x2 - 5x - 12 = 0

2x2 + 3x - 8x - 12 = 0

x(2x + 3) - 4(2x + 3) = 0

(x - 4) (2x + 3) = 0

x - 4 = 0 or 2x + 3 = 0

x = 4 or 2x = -3

x = -3/2

So, the solutions are x = 4 or x =-3/2.

Problem 11 :

2 = 9x - 5x2

Solution:

5x2 - 9x + 2 = 0

Comparing 5x2 - 9x + 2 = 0 and ax2 + bx + c = 0, we get

a = 5, b = -9 and c = 2

By using quadratic formula,

x = -b±b2-4ac2ax = -(-9)±(-9)2-4(5)(2)2(5)x = 9±81-4010x=9±4110x =9+4110 or x=9-4110

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