Question

4. Find CD and X . (3 points) x ^ 3 + 20 30 D x ^ 8 + 22x - 120 will mark brainliest

Answer 1

Answer:

CD = 15

x = 5

Step-by-step explanation:

Since BF ≅ FD and AE ≅ EC, then $EF = \frac{AB + CD}{2}$

So, $30 = \frac{x^{2} +20 + x^{2} + 22x - 120}{2}$

$60 = 2x^{2} + 22x - 100$

$2x^{2} + 22x - 160 = 0$

$2(x^{2} + 11x - 80) = 0$

2(x - 5)(x + 16) = 0

x = 5  or x = -16

If x = 5, then CD = $5^{2} +22(5) - 120 = 25 + 110 - 120 = 15$  

Ix x = -16, then CD = will be a negative number which it cannot be.