Question

factories 84-2r-2r2​

Answer 1

ANSWER:

• Required Factorisation = 2(r+7)(-r+7)

GIVEN:

• P(x) = 84-2r-2r²

TO FIND:

• Factorise the above expression.

SOLUTION;

= 84-2r-2r²

= 2(-r²-r+42)

= 2(-r²-7r+6r+42)

= 2[-r(r+7) +6(r+7)]

= 2(r+7)(-r+6)

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