Question

factorise 1-a-72a^2
Math ch 12
Ex 12.2​

Answer 1

Answer:

Step-by-step explanation:

$=1-a-72a^{2}\\\\Multiple By -1\\\\=-1+a+72a^{2}\\=72a^{2}+a-1\\=72a^{2}-9a+8a-1\\=9a(8a-1)+1(8a-1)\\=(8a-1)(9a+1)$

Answer 2

Answer:

1/9 and -1/8

Step-by-step explanation:

1 - a - 72a^2     => 72a^2 + a - 1

By using quadratic formula, x = -b +- √b^2-4ac / 2a

= a = -1 +- √1 + 4x72 / 2x72

     = -1 +- √289 / 144

     = -1 +- 17 / 144

= a = -1 + 17 / 144              

     = 16 / 144

    => 1/9

  and

= a = -1 - 17 / 144

     = -18 / 144

    => -1/8

Therefore, a = 1/9 and -1/8.