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2 years ago

Which quadratic equation has solutions x=8 and x=−1?

1 answer:

7 0

There are two ways you can do this

$Using the formula$

${x}^{2} - (sum \: of \: roots)x + poduct \: of \: roots = 0$

${x}^{2} - (8+-1)x + - 1 \times 8 = 0$

${x}^{2} - 7x - 8 = 0$

$Working backwards$

$x = 8 \: or \: x = - 1$
$\Rightarrow x-8=0 \: or \: x+1=0$

$\Rightarrow (x-8)(x + 1)=0$
$\Rightarrow {x}^{2} + x -8x - 8 = 0$
$\Rightarrow {x}^{2} - 7x - 8 = 0$

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A contaminant is leaking into a lake at a rate of R(t) = 1400e0.06t gallons/h. Enzymes have been added to the lake that neutrali

ruslelena [56]

Answer:

Step-by-step explanation:

Rate of leakage, R(t) = 1400 e^0.06t gallons/h

fraction remains , S(t) = e^(-0.32t)

initial contaminant = 1000 gallon

gallons contaminant present after t hour is S(t) R(t)

G(t) = S(t) R(t)

$G(t) = 1400 e^{0.06t}\times e^{-0.32t}$

$G(t) = 1400 e^{- 0.26t}$

Put t = 18 hours

$G(t) = 1400 e^{- 0.26\times 18}$

Taking log on both the sides

ln G = ln 1400 - 0.26 x 18

ln G = 7.244 - 4.68

ln G = 2.564

G = 13 gallons

5 0

2 years ago

The physician tells a woman who usually drinks 5 cups of coffee daily to cut down on her coffee consumption by 75%. If this woma

Maru [420]

Answer:

Step-by-step explanation:

5 cups per day.....1 cup = 8oz.....so 5 cups = (5 * 8) = 40 oz

cut down by 75%....means ur only drinking 25%

25% of 40 oz =

0.25(40) = 10 oz per day <===

6 0

2 years ago

What are the x- and y- coordinates of point E, which partitions the directed line segment from J to K into a ratio of 1:4? (–13,

Lana71 [14]

I added a screenshot of the complete question.

Answer:

(-7, -1)

Explanation:

The formulas given to calculated the x and y coordinates are as follows:

$x = (\frac{m}{m+n})(x_{2}-x_{1}) + x_{1}\\\\y = (\frac{m}{m+n})(y_{2}-y_{1}) + y_{1}$

Let's define the variables used:

(x₁ , y₁) are the coordinates of the first point while (x₂ , y₂) are the coordinates of the second point.

We are given that the segment is directed from J to K, therefore:

First point is J ..........> (x₁ , y₁) is (-15, -5)

Second point is K ....> (x₂ , y₂) is (25, 15)

m and n defined the portion of the partitioned segment (JE : EK). It is given that this ratio is 1:4. Therefore:

m = 1 and n = 4

Finally, let's substitute with these variables in the equations as follows:

$x = (\frac{1}{1+4})(25-(-15)) + (-15) = -7\\\\y = (\frac{1}{1+4})(15-(-5)) + (-5) = -1$

Based on the above, the coordinates of point E are (-7, -1)

Hope this helps :)

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2 years ago

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At Northwest Highschool, there are 1472 students in the junior class and 1012 students in the senior class. To let the juniors w

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The awnser would be A

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2 years ago

In isosceles △ABC (AC = BC) with base angle 30° CD is a median. How long is the leg of △ABC, if sum of the perimeters of △ACD an

SIZIF [17.4K]

Note necessary facts about isosceles triangle ABC:

The median CD drawn to the base AB is also an altitude to tha base in isosceles triangle (CD⊥AB). This gives you that triangles ACD and BCD are congruent right triangles with hypotenuses AC and BC, respectively.
The legs AB and BC of isosceles triangle ABC are congruent, AC=BC.
Angles at the base AB are congruent, m∠A=m∠B=30°.

1. Consider right triangle ACD. The adjacent angle to the leg AD is 30°, so the hypotenuse AC is twice the opposite leg CD to the angle A.

AC=2CD.

2. Consider right triangle BCD. The adjacent angle to the leg BD is 30°, so the hypotenuse BC is twice the opposite leg CD to the angle B.

BC=2CD.

3. Find the perimeters of triangles ACD, BCD and ABC:

$P_{ACD}=AC+CD+AD=2CD+CD+AD=3CD+AD;$

$P_{BCD}=BC+CD+BD=2CD+CD+AD=3CD+AD;$

$P_{ABC}=AC+BC+AB=2CD+2CD+AD+BD=4CD+2AD.$

4. If sum of the perimeters of △ACD and △BCD is 20 cm more than the perimeter of △ABC, then

$P_{ACD}+P_{BCD}=P_{ABC}+20,\\ \\3CD+AD+3CD+AD=4CD+2AD+20,\\ \\6CD+2AD=4CD+2AD+20,\\ \\2CD=20.$

5. Since AC=BC=2CD, then the legs AC and BC of isosceles triangles have length 20 cm.

Answer: 20 cm.

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2 years ago

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