Wednesday

August 27, 2014

August 27, 2014

Posted by **carol** on Wednesday, May 4, 2011 at 4:02pm.

x + 4 = -18 => x = -22

or

(x – 7) = -18 => x = -11

However, at least one of these solutions fails to work when substituted back into the original equation. Why is that? Please help Eric to understand better; solve the problem yourself, and explain your reasoning.

- math -
**Reiny**, Wednesday, May 4, 2011 at 6:14pmEric does not understand the concept

It only works if the product is zero

so expand ....

x^2 - 3x - 28 = -18

x^2 - 3x - 10 = 0

(x-5)(x+2) = 0

x = 5 or x = -2

**Related Questions**

Algebra - In solving the equation (x + 3)(x + 1) = 48, Eric stated that the ...

algebra - 1. In solving the equation (x + 3)(x + 1) = 48, Eric stated that the ...

algbera - In solving the equation (x + 3)(x + 1) = 48, Eric stated that the ...

intermediate algebra - In solving the equation (x-1)(x+2)=30. Eric stated that ...

Math - I don't understand how to solve this problem: In solving the equation (x...

algebra - solving the equation (x+4)(x-4)=9 Eric stated that the solution would ...

South - In solving the equation (x + 1)(x – 2) = 54, Eric stated that the ...

Math - In solving the eqaution(x+4)(x-4),Eric stated thatthe solution would be x...

intermediate algebra - in solving the equation (x+4)(x-4)=9 eric stated the ...

algebra - in solving the equation (x +2)(x - 2) = 32 eric stated the solution to...