Question

factorise 15x⁴+3x²-18​

Answer 1

15x^4 + 3x^2 - 18

3[ 5x^4 + x^2 - 6 ]

let us consider y = x^2

3[5y^2 + y - 6 ]

3[5y^2 + 6y - 5y -6 ]

3[ y (5y + 6 ) -1 (5y + 6 ) ]

3[(y-1) (5y + 6) ]

Again replacing y = x^2

3[( x^2 - 1) ( 5x^2 + 6 )]

let us consider 1 as 1^2

3[ ( x^2- 1^2 )( 5x^2 + 6 ) ]

Using - x^2 - y^2 = (x+y) (x-y)

3[ ( x + 1 ) ( x - 1 ) ( 5x^2 + 6 ) ]

Ans. = 3 (x + 1) (x - 1) ( 5x^2 + 6 )

Answer 2

Answer:

3(5x²+6) (x-1) (x+1)

Here is your solution:



= 15x⁴+3x²-18

= 3(5x⁴ + x² - 6)

= 3{5x⁴ +(6-5)x² 6}

= 3(5x⁴ +6x² -5x² -6)

= 3{x²(5x² +6) -1(5x² +6)}

= 3(5x² +6) (x² -1)

= 3(5x² +6) (x-1) (x+1)

Hope it's helpful .