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lions [1.4K]
3 years ago
11

PLease solve this factorize: x^2-4x-21+10y-y^2

Mathematics
2 answers:
natita [175]3 years ago
5 0

Answer:

(x - y + 3)(x + y - 7)

Step-by-step explanation:

x^2 - 4x - 21 + 10y - y^2

= x^2 - y^2 +10y - 4x - 21

= (x - y)(x + y) + 10y - 4x - 21

This is a stab in the dark - I think this might factor to (x - y + 3)(x + y - 7)  or

(x - y - 7)(x + y + 3) - I think I've come across one like this before.

Lets try the first one:

(x - y + 3)(x + y - 7) = x^2 + xy - 7x - y^2 - xy +3y + 3x + 7y - 21

= x^2 -7x + 3x -21 + 10y  - y^2.

This is correct but isn't a very logical way to do this. There must be a better way!

The logical way is  by reducing the expression to the difference of 2 squares: (x - 2)^2 - (y - 5)^2

This factors to ( x + y -7)(x - y + 3).

kompoz [17]3 years ago
4 0

 

\displaystyle\bf\\x^2-4x-21+10y-y^2=\\=x^2-y^2 -7x+3x+7y+3y -21=\\\\=(x-y)(x+y) -7x+7y +3x+3y-3\cdot7=\\\\=\boxed{\bf(x+y-7) (x-y+3)}

 

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A rocket carrying fireworks is launched from a hill 60 feet above a lake. The rocket will fall into the lake after exploding at
castortr0y [4]

Answer:

<h3>A) 204m</h3><h3>B) 188m</h3>

Step-by-step explanation:

Given the rocket's height above the surface of the lake given by the function h(t) = -16t^2 + 96t + 60

The velocity of the rocket at its maximum height is zero

v = dh/dt = -32t + 96t

At the maximum height, v  = 0

0 = -32t + 96t

32t = 96

t = 96/32

t = 3secs

Substitute t = 3 into the modeled function to get the maximum height

h(3) = -16(3)^2 + 96(3) + 60

h(3) = -16(9)+ 288 + 60

h(3) = -144+ 288 + 60

h(3) = 144 + 60

h(3) = 204

Hence the maximum height reached by the rocket is 204m

Get the height after 2 secs

h(t) = -16t^2 + 96t + 60

when t = 2

h(2) = -16(2)^2 + 96(2) + 60

h(2) = -64+ 192+ 60

h(2) = -4 + 192

h(2) = 188m

Hence the height of the rocket after 2 secs is 188m

3 0
3 years ago
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3 years ago
Slope:-2;y intercept: 3
drek231 [11]

Answer:

y = -2x + 3

Step-by-step explanation:

Hope this helps!

5 0
3 years ago
Use the quadratic formula to solve the equation <br> 25x^2-30x+25=0
Reika [66]

Answer: x=\frac{3}{5}+i\frac{4}{5},\:x=\frac{3}{5}-i\frac{4}{5}

Step-by-step explanation:

25x^2-30x+25=0

x_{1,\:2}=\frac{-\left(-30\right)\pm \sqrt{\left(-30\right)^2-4\cdot \:25\cdot \:25}}{2\cdot \:25}

\sqrt{\left(-30\right)^2-4\cdot \:25\cdot \:25}

=\sqrt{30^2-4\cdot \:25\cdot \:25}

=\sqrt{30^2-2500}

=i\sqrt{2500-30^2}

=40i

x_{1,\:2}=\frac{-\left(-30\right)\pm \:40i}{2\cdot \:25}

x_1=\frac{-\left(-30\right)+40i}{2\cdot \:25},\:x_2=\frac{-\left(-30\right)-40i}{2\cdot \:25}

x=\frac{3}{5}+i\frac{4}{5},\:x=\frac{3}{5}-i\frac{4}{5}

8 0
2 years ago
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Kazeer [188]

Answer:

-1/5

Step-by-step explanation:

3/5 is greater than 2/5, so your answer goes into the negatives

6 0
3 years ago
Read 2 more answers
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