Question

Which of the following is equivalent to 4-4a-(5+a)(5-a)

Answer 1

Answer:

${a}^{2}-4a - 21 = 0$

Step-by-step explanation:

$4 - 4a - (5 + a)( 5- a) = 0$

$4 - 4a - (25 - 5a + 5a - {a}^{2} = 0$

$4 - 4a - 25 + 5a - 5a + {a}^{2} = 0$

${a}^{2} - 4a + 5a - 5a + 4 - 25 = 0$

${a}^{2} - 4a - 21 = 0$