If a(a + 4) = 21 and b(b + 4) = 21, where a ≠ b, then a + b = Choose the correct choice from the following options
A) −4	B) −2	C) 2	D) 46	E) 48
a(a + 4) = 21   =&gt; we have a = 3 or -7   also b(b + 4) = 21   =&gt; b = 3 or -7   given a ≠ b   1) when a =3, b= -7 and a + b = -4   1) when a = -7, b= 3 and a + b = -4   −4nswer choice −4
<result>A</result>
If a(a + 4) = 21 and b(b + 4) = 21, where a ≠ b, then a + b =