what is x in this expression (x-1)(x+6)

Question

im stuck at school and i cant get help what is the answer these questions

(x-1)(x+6) and  (x-5)2 and  (x+3)(x-3) and  (x+a)2

Answer 1

Lolly,

 

I'm not sure if this is what is confusing you or not, but I though that the following idea might be helpful:

 

Any variable (for example, x) will only have a specific number value if it is part of a mathematical sentence.  In other words, if there is an equal sign or inequality symbol as part of the problem, then you will be able to solve for x (for examples, see Salimat's answer above).  If there is not an equal sign or inequality symbol (so, if the problem only gives you a mathematical expression), then you will not be able to solve for x.  When you can't solve for x, usually the only math that is done is done to simplify the expression or write it in another way (see Vivian's answer above).

 

I hope this helps!

 

~Patty

Answer 2

Hi Lolly;

I am not certain what you mean by "what is x in this expression".  Because it is an expression, there is no solution to x.  However, I will do the best I can to help.

 

(x-1)(x+6)

Let's FOIL...

FIRST...(x)(x)=x²

OUTER...(x)(6)=6x

INNER...(-1)(x)=-1x=-x

LAST...(-1)(6)

x²+6x-x-6

x²+5x-6

----------------------

(x-5)2

I believe this is...

(x-5)²

This is also...

(x-5)(x-5)

x²-5x-5x+25

x²-10x+25

------------------------

(x+3)(x-3)

x²-3x+3x-9

x²-9

------------------------

(x+a)2

(x+a)²

(x+a)(x+a)

x²+ax+ax+a²

x²+2ax+a²

 

If you need more instruction on the FOIL, please let me know.

Answer 3

(x-1)(x+6)=0

x-1=0, x+6=0

  +1+1   -6 -6

x=1        x=-6

 

(x-5)2=0

2x-10=0

    +10 +10

2x=10

2     2

x=5

 

(x-3)(x+3)=0

x-3=0, x+3=0

 +3 +3   -3  -3

x=3         x=-3

 

(x+a)2=0

2x+2a=0

    -2a  -2a

2x=-2a

2    2

x=-a