Answer:
the modulus of a complex number z = a + bi is:
Izl= √(a²+b²)
The fact that n is complex does not mean that n doesn't has a real part, so we must write our numbers as:
m = 2 + 6i
n = a + bi
Im + nl = 3√10
√(a² + b²+ 2²+ 6²)= 3√10
√(a^2 + b^2 + 40) = 3√10
squaring both side
a²+b²+40 = 3^2*10 = 9*10 =90
a²+b²= 90 - 40
a²+b²=50
So,
|n|=√(a^2 + b^2) = √50
The modulus of n must be equal to the square root of 50.
now
values a and b such
a^2 + b^2 = 50.
for example, a = 5 and b = 5
5²+5²=25+25= 50
Then a possible value for n is:
n = 5+5i
Answer:
make Y the subject in eqn........ 1
y + 7 = 2x
y = 2x - 7...........eqn 3
put y = 2x - 7 into eqn 2
x² - xy + 3y² = 15
x² - x(2x - 7) + 3(2x - 7)(2x - 7) = 15
x² - 2x² + 7x + 3(4x² + 14x -14x + 21) = 15
x² - 2x² + 7x + 12x² + 42x - 42x + 63 = 15
x² - 2x² + 7x + 12x² + 63 = 15
x² - 2x² + 12x² + 7x + 63 = 15
11x² + 7x + 63 - 15 = 0
11x² + 7x + 48 = 0
11x² + 7x = - 48
11x²/11 + 7x/11 = - 48/11
x² + 7x
11 times with a remainder of 5
