# Solve this eqution: (x+3)(x+9)

Asked on by soul001

kjcdb8er | Teacher | (Level 1) Associate Educator

Posted on

As written, the expression (x + 3)(x + 9) is not an equation, so there is nothing to solve. This expression may be simplified by multiplying through the parenthesis.

(x + 3)(x + 9) = (x + 3)*x + (x + 3)*9

= x^2 + 3x + 9x + 3*9

= x^2 + 12x + 27

Often expressions such as that given are set equal to zero, in which case there is an equation.

(x + 3)(x + 9) = 0 may be solved by remembering that if a*b = 0, then either a or b must be equal to zero. Thus either x + 3 = 0 or x + 9 = 0, meaning that x = -3 or x = -9

taangerine | Student, Grade 12 | (Level 1) Valedictorian

Posted on

To solve this equation, we can use FOIL -- First, Outside, Inside, Last

• (x)(x)+(9)(x)+(3)(x)+(9)(3)

Simplify

• `x^(2)+9x+3x+27`
• `x^(2)+12x+27`

crystaltu001 | Student, Grade 10 | (Level 1) Valedictorian

Posted on

(x+3)(x+9)

Use the foil method and distribute the first  x and the 3 to the other numbers.

x*x= x^2

x*9= 9x

3*x= 3x

3*9=27

The answer is x^2+12x+27

acompanioninthetardis | Student, Undergraduate | (Level 1) Valedictorian

Posted on

(x+3)×(x+9). You have to take one part I.e. X and then multiply it to the entire second equation I.e. x+9. And then put the same sign as in the middle in this case it's addition and then repeat the first step but multiply by 3 so you get something like this X squared + 9x +  3x + 27. Then simplify to x^2 +12x+27.

zumba96 | Student, Grade 11 | (Level 3) Valedictorian

Posted on

For (x+3)(x+9) you have to use FOIL

Take; x(x+9)+3(x+9)

= x^2+9x+3x+27

Combine Like Terms

x^2+12x+27

Wiggin42 | Student, Undergraduate | (Level 2) Valedictorian

Posted on

I am assuming the problem is this:

(x+3)(x+9) = 0

We know that either

x + 3 = 0    or    x + 9 = 0

Solve for the two different x values independently and get:

x = -3      x = -9

Depending on the real life application (if there is one for this problem) one of the answers is extraneous.

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

Posted on

`(x+3)(x+9)`

use the foil method, multiply every number in the first parentheses by every number in the second parentheses:

`(x+3)(x+9) `

`x xx x=x^2 `

`x xx 9=9x `

`3xxx=3x`

`3xx9=27`

`x^2+9x+3x+27 `

combine like terms which would be `9x+3x=12x`

`x^2+12x+27`

Jyotsana | Student, Grade 10 | (Level 1) Valedictorian

Posted on

Box Method

(x+3)(x+9)

x*x=x^2

x*9=9x

3*x=3x

3*9=27

x^2+9x+3x+27

x^2+12x+27

mh41602 | Elementary School Teacher | (Level 1) eNoter

Posted on

These questions are made into equations so you can solve them. The key is to make both sides of the equation equal. I call it balancing the scale.