acme asked in Science & MathematicsMathematics · 2 months ago

# Maths question help ?

Solve by factorising x squared + 9x+20=0

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• 2 months ago

x^2 + 9x + 20 = 0

(x + 4)(x + 5) = 0

x + 4 =0 ,  x + 5 = 0

x = - 4, x = - 5

x = - 4, - 5 answer//

• 2 months ago

x^2 + 9x + 20 = 0

x^2 + 5x + 4x + 20 = 0

x(x + 5) + 4(x + 5) = 0

(x + 5)(x + 4) = 0

Solutions:

x = -5

x = -4

• Anonymous
2 months ago

I did it in my mind the answer

Solutions:

x = -5

x = -4

• Como
Lv 7
2 months ago

( x  +  5 ) ( x + 4 ) = 0

x = - 5 , x = - 4

• sepia
Lv 7
2 months ago

x^2 + 9x + 20 = 0

(x + 5)(x + 4) = 0

Solutions:

x = -5

x = -4

• 2 months ago

distribute 42 birds in 7 cages each contain an odd number?

• Ian H
Lv 7
2 months ago

Here is an explanation of how to do this example.

If you multiply out two factors such as (x + a)(x + b) you get

x^2 + (a + b)x + a*b,

so now compare that with your example

x^2 + 9x + 20 = 0

You need two numbers that add to make 9 and multiply to make 20.

That is easy, because 4 *5 = 20 and 4 + 5 = 9, so now you can write

x^2 + 9x + 20 = (x + 4)(x + 5) = 0

Either x + 4 = 0. which makes x = -4, or,

x + 5 = 0. which makes x = -5

You were expected to know this method already, so, I suggest that

you remember it now as it will be needed many times.

• 2 months ago

You must be the laziest child in existence. Google it.

• Peter2 months agoReport

There is no need  to call her/him that. I forget things too after a while

• Anonymous
2 months ago

YOU ARE LAZY AND DISHONEST BY ASKING STRANGERS TO DO YOUR HOMEWORK. IF YOU TOLD YOUR TEACHER YOU DID IT YOU WOULD FAIL.

And you SHOULD FAIL as you are cheating.

• 2 months ago

x^2 + 9x + 20 = 0

(x + 5)(x + 4) = 0

x = -5 or x = -4