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Lostsunrise [7]
3 years ago
7

2x2 - 4x –9 = 0 Completing the swuare

Mathematics
1 answer:
ASHA 777 [7]3 years ago
4 0

Step-by-step explanation:

(a-b)^2=a^2-2ab+b^2\\\\2x^2-4x-9=0\qquad|\text{add 9 to both sides}\\\\2x^2-4x-9+9=0+9\\\\2x^2-4x=9\qquad|\text{divide both sides by 2}\\\\\dfrac{2x^2}{2}-\dfrac{4x}{2}=\dfrac{9}{2}\\\\x^2-2x=4.5\\\\x^2-2\cdot x\cdot1=4.5\qquad|\text{add}\ 1^2\ \text{to both sides}\\\\x^2-2\cdot x\cdot1+1^2=4.5+1^2\\\\(x-1)^2=5.5\iff x-1=\pm\sqrt{5.5}\qquad|\text{add 1 to both sides}\\\\x=1-\sqrt{5.5}\ \vee\ x=1+\sqrt{5.5}

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A tree 12m high is broken by the wind in such a way that its top touches the ground and makes an angle 60° with the ground. at w
Katena32 [7]

The height of broken part of tree from ground is 5.569m.

Justification:

Let BD is a tree of height 12 m.

<u>Suppose it got bent at a point C and let the part CD take the position CA, meeting the ground at A</u>.

i.e., CD = AC = h m

<u>Broken part makes 60° angle from ground</u>

So, ∠BAC = 60°

<u>Now, height of remaining part of tree</u> = (12 – h)m.

In right angled ∆ABC,

sin 60° = BC/AC

⇒ √3/2 = (12 - h)/h

⇒ √3h = 2(12 – h)

⇒ √3h = 24 – 2h

⇒ √3h + 2h = 24

⇒ h(√3 + 2) = 24

⇒ h(1.732 + 2) = 24

⇒ h(3.732) = 24

⇒ h = 24/3.732 = 6.4308 m

<u>Hence, height of broken tree from ground</u>

⇒ BC = 12 – h

⇒ 12 – 6.4308 = 5.569m

<u>Hence, tree is broken 5.569 m from ground</u>.

<u>Note</u>: See attached picture.

4 0
3 years ago
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Answer:

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Step-by-step explanation:

If x is the volume of solution B:

0.06 (500) + 0.20 x = 0.10 (500 + x)

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Question

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the rate is 81 : 9

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False I think it is if I’m right
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