Solve the following quadratic equations:
2x2 – (3 + 7i)x + (9i – 3) = 0
2x2 – (3 + 7i)x + (9i – 3) = 0
Given 2x2 – (3 + 7i)x + (9i – 3) = 0
Recall that the roots of quadratic equation ax2 + bx + c = 0, where a ≠ 0, are given by
Here, a = 2, b = –(3 + 7i) and c = (9i – 3)
By substituting i2 = –1 in the above equation, we get
By substituting –1 = i2 in the above equation, we get
We can write 16 + 30i = 25 – 9 + 30i
⇒ 16 + 30i = 25 + 9(–1) + 30i
⇒ 16 + 30i = 25 + 9i2 + 30i [∵ i2 = –1]
⇒ 16 + 30i = 52 + (3i)2 + 2(5)(3i)
⇒ 16 + 30i = (5 + 3i)2 [∵ (a + b)2 = a2 + b2 + 2ab]
By using the result 16 + 30i = (5 + 3i)2, we get
[∵ i2 = –1]
Thus, the roots of the given equation are 3i and.