Question

please solve 7th and 8th one

Answer 1

7) height of pole 60 m

8) value of k = -9/4

Answer 2

7)

Answer: 60 m

Step-by-step explanation:

Let A be the top point of the pole, B be the bottom point of the pole at the ground, and C be the farthest point of the shadow from the pole.

Draw right triangle ABC.

BC = 20√3 m

∠ACB = 60°

We've to find AB.

Tan 60 = AB / BC

√3 = AB / 20√3

AB = √3 × 20√3

AB = 60 m

8)

Answer: - 9/4  or  - 2 and 1/4

Step-by-step explanation:

$p(x)=3x^2+2kx-3=0$

If  - 1/2  is a solution of p(x), then p(- 1/2) = 0.

$p(-\frac{1}{2})=3(-\frac{1}{2})^2+2k(-\frac{1}{2})-3=0 \\ \\ p(-\frac{1}{2})=3(\frac{1}{4})-\frac{2k}{2}-3=0 \\ \\ p(-\frac{1}{2})=\frac{3}{4}-k-3=0$

$\frac{3}{4}-k-3=0 \\ \\ k=\frac{3}{4}-3 \\ \\ k=-\frac{9}{4} \\ \\ k=-2\frac{1}{4}$

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