One of the solutions to x2 − 2x − 15 = 0 is x = −3. What is the other solution?

2 answers:

7 0

If you factor the equation you can see what the solutions are. Two factor a quadratic of the form ax^2+bx+c, find two values which satisfy two conditions...

jk=ac=-15 and j+k=b=-2 so j and k must be -5 and 3 so the factors are:

(x-5)(x+3)

So the other solution is x=5

Tcecarenko [31]3 years ago

6 0

The answer is D) X=5 on E2020 (:

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frosja888 [35]

Answer:

11.8

Step-by-step explanation:

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3 years ago

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The Length of a rectangle exceeds its breadth by 9 cm. if length and breadth are each increased by 3 cm, the area of new rectang

gizmo_the_mogwai [7]

Answer:

Breadth = 8 cm

Length = 17 cm

Step-by-step explanation:

Given rectangle:

Breadth = x cm

Length = x + 9 cm

Area = length * breadth

= x * (x + 9)

= x² + 9x

Rectangle with length and breadth increased:

Breadth = x + 3 cm

Length = x + 9 + 3 = x + 12 cm

Area = 84 + (x² + 9x) cm²

(x +3) * (x +12) = 84 + x² + 9x

Use FOIL method

x*x + x*12 + 3*x + 3*12 = 84 + x² + 9x

x² + 12x + 3x + 36 = 84 + x² + 9x {add the like terms}

x² + 15x + 36 = 84 + x² + 9x

x² + 15x + 36 - 84 - x² - 9x = 0

6x - 48 = 0

6x = 48

x = 48/6

x = 8

Breadth = x = 8 cm

Length = x + 9 = 8 +9 = 17 cm

7 0

3 years ago

Find the equation of all tangent lines having slope of -1 that are tangent to the curve y=(9)/(x+1)

fredd [130]

Answer:

$f(x)=\frac9{x+1}\\ f'(x)=-\frac9{(x+1)^2}\\ f'(x)=-1\ \iff\ -\frac9{(x+1)^2}=-1\ \to \ \frac9{(x+1)^2}=1\ \to \ (x+1)^2=9\\ |x+1|=3\ \to \ x+1=3\ \vee\ x+1=-3\\ x_1=2\ \vee\ x_2=-4\\ f(x_1)=f(2)=\frac9{2+1}=3\\ f(x_2)=f(-4)=\frac9{-4+1}=-3$