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ra1l [238]
3 years ago
5

For which value of c is the line y=3x+c a tangent to the parabola with equation y=x^2-5x+7

Mathematics
1 answer:
Alik [6]3 years ago
6 0
Equating the y's:-

3x + c = x^2 - 5x + 7

x^2  - 8x +7 - c = 0

If y = 3x + c is a tangent then there  will be duplicate solutions to this equation 
That is the discriminant b^2 - 4ac = 0. So we have:-

(-8)^2 - 4 * 1 * (7 -c)  = 0
64 -28 + 4c = 0
4c  = - 36

so c = -9  answer
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3. if kx² + 2x + k = -kx have equal roots, find the values of k.<br>​
crimeas [40]

Answer:

k = - \frac{2}{3} , k = 2

Step-by-step explanation:

Using the discriminant Δ = b² - 4ac

The condition for equal roots is b² - 4ac = 0

Given

kx² + 2x + k = - kx ( add kx to both sides )

kx² + 2x + kx + k = 0 , that is

kx² + (2 + k)x + k = 0 ← in standard form

with a = k, b = 2 + k and c = k , thus

(2 + k)² - 4k² = 0 ← expand and simplify left side

4 + 4k + k² - 4k² = 0

- 3k² + 4k + 4 = 0 ( multiply through by - 1 )

3k² - 4k - 4 = 0 ← in standard form

(3k + 2)(k - 2) = 0 ← in factored form

Equate each factor to zero and solve for k

3k + 2 = 0 ⇒ 3k = - 2 ⇒ k = - \frac{2}{3}

k - 2 = 0 ⇒ k = 2

5 0
3 years ago
Evaluate 5 - 44 * (-0.75) - 18 / 2/3 * 0.8 + (-4/5)
jenyasd209 [6]

Answer:

15.6

step by step explanation:

5-44• (-0.75) - 18 ÷ 2/3 • 0.8 + (-4/5)

= 5 + 33 - 27*0.8 - 0.8

= 5 + 33 -21.6 - 0.8

= 15.6.

8 0
3 years ago
A student wrotw a variable expression n-5 for the word phrase n less than 5. explain the students error
zheka24 [161]
Less than does mean minus, but when the question says less than some number, that number goes first. should have written 5-n
3 0
3 years ago
The thied-grade class is going on a field trip by bus to the museum.The bus leaves the school at 9:45 A.M. The bus ride takes 47
erica [24]
10:32 A:M in 15 minutes it will be 10:00 and then 32 minutes remaining
5 0
3 years ago
Read 2 more answers
Find the length of the arc of a circle with radius of 20 centimeters intercepted by a central angle of 45 degrees
oksian1 [2.3K]

If the radius is 20cm, the circumference is

C = 2\pi r = 40\pi centimeters.

Now, 45° is one eighth of a whole turn, so the arc intercepted by a 45° angle is one eighth of the whole circumference, so the answer is

\dfrac{40\pi}{8} = 5\pi

8 0
3 years ago
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