Question

4xsquare+8x-5 answer​

Answer 1

Question should be:

• Factorise 4x²+8x-5 OR
• Find the zeros of 4x²+8x-5.

ANSWER

• Roots of the given polynomial is -5/2 and 1/2

GIVEN:

• P(x) = 4x²+8x-5

TO FIND:

• Roots of the given polynomial.

SOLUTION:

= 4x²+8x-5

= 4x²+10x-2x-5

= (4x²+10x) +(-2x-5)

= 2x(2x+5)-1(2x+5)

= (2x+5)(2x-1)

Roots :

=> (2x+5)(2x-1) = 0

Either (2x+5) = 0

=> 2x = -5

=> x = -5/2

Either (2x-1) = 0

=> 2x = 1

=> x = 1/2

Roots of the given polynomial is -5/2 and 1/2

NOTE:

Some important formulas:

(a+b)² = a²+b²+2ab

(a-b)² = a²+b²-2ab

(a+b)(a-b) = a²-b²

(a+b)³ = a³+b³+3ab(a+b)

(a-b)³ = a³-b³-3ab(a-b)

a³+b³ = (a+b)(a²+b²-ab)

a³-b³ = (a-b)(a²+b²+ab)

(a+b)² = (a-b)²+4ab

(a-b)² = (a+b)²-4ab