Question

which equation has a real component of 4. A. x2-8x+16= -21 B. x2-4x+4= -25 C. x2 +8x +16 = -21 D. x2 +4x + 4 = -25

Answer 1

When we take a look at x² - 8x + 16 = -21

x² - 8x + 16 + 21 = 0

x² - 8x + 37 =0

Using quadratic formula

$x\text{ = }\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}$

a = 1 b =-8 c = 37

substitute the values into the quadratic formula

$x=\frac{8\pm\sqrt[]{64-148}}{2}$$x=\frac{8}{2}\pm\frac{\sqrt[]{84}i}{2}$$x=4\pm4.58i$

Hence, option A has a real component of 4