(3x + 1) (2x - 1) = 144
6 x^2 - x - 145 = 0
use quadratic formula to find x
What is the value of x if the length and the breadth of a rectangle are (3x +1)cm and( 2x -1)cm respectively and whose area is 144cm² ?
2 answers
L = length
B = breadth
A = Area
A = L ∙ B
( 3 x + 1 ) ∙ ( 2 x - 1 ) = 144
6 x² + 2 x - 3 x - 1 = 144
6 x² x - 1 = 144
Subtract 144 to both sides
6 x² - x - 145 = 0
The solutions are:
x = - 29 / 6 and x = 5
Length and breadth cannot be negative so x = 5 cm
By the way:
L = ( 3 x + 1 ) = 3 ∙ 5 + 1 = 15 + 1 = 16 cm
B = ( 2 x - 1 ) = 2 ∙ 5 - 1 = 10 - 1 = 9 cm
A = 16 cm ∙ 9 cm = 144cm²
B = breadth
A = Area
A = L ∙ B
( 3 x + 1 ) ∙ ( 2 x - 1 ) = 144
6 x² + 2 x - 3 x - 1 = 144
6 x² x - 1 = 144
Subtract 144 to both sides
6 x² - x - 145 = 0
The solutions are:
x = - 29 / 6 and x = 5
Length and breadth cannot be negative so x = 5 cm
By the way:
L = ( 3 x + 1 ) = 3 ∙ 5 + 1 = 15 + 1 = 16 cm
B = ( 2 x - 1 ) = 2 ∙ 5 - 1 = 10 - 1 = 9 cm
A = 16 cm ∙ 9 cm = 144cm²
1 answer