Question

If a + b = 4 and ab = -12, find a-b and a+b​

Answer 1

Answer:

26

Step-by-step explanation:

a-b=4______(1)

a+b=6______(2)

from 1 and 2 we get

2a=10

a=5

put a=5 in 2 we get

b=1

so ab=5×1=5

and a^2+b&2=(5)^2+(1)^2=25+1=26

Answer 2

$ab = - 12 \\ b = \frac{ - 12}{a}$

$a + b = 4 \\ a - \frac{12}{a} = 4 \\ \frac{ {a}^{2} - 12}{a} = 4 \\ {a }^{2} - 4 a - 12 = 0 \\ {a}^{2} - 6a + 2a - 12 = 0 \\ a(a - 6) + 2(a - 6) = 0 \\ (a + 2)(a - 6) = 0$

$a \: could \: be \: - 2 \: or \: 6$

$b = \frac{ - 12}{2} \: or \: \frac{ - 12}{ - 6 } \\ b = - 6 \: or \: 2$

$a - b = - 2 + 6 = 4 \: or \: 6 - 2 = 4$

$a + b = - 2 - 6 = - 8 \: or \: 6 + 2 = 8$