How can I get help with Sat prep for solving the equation ab-1/b?

[boricua_2004]

1/(1/a)-(1/b) a cannot = 0 b cannot equal= 0 and a cannot equal b



i would gladly appreciate if someone can help me

 

[rocomath]

Ok ... so what is the problem asking?

 

[boricua_2004]

just asking to simplify the problem

 

[rocomath]

\frac{1}{\frac{1}{a}}-\frac{1}{b}

Multiply the numerator of 1/(1/a) by a and the denominator (1/a) by a.

Also, next time post this in the Precalculus section.

 

[boricua_2004]

is that wat you think it is or the answer and how did you get there and from my answer choices that's not one them

 

[rocomath]

is that wat you think it is or the answer and how did you get there and from my answer choices that's not one them

I'm not going to do it for you.

Continue working it with what I suggested with my other reply.

 

[boricua_2004]

ok no prob

 

[boricua_2004]

ok i have this so far a-1/b I am i in the right path

 

[rocomath]

ok i have this so far a-1/b I am i in the right path

Good!

So what is the requirement to add fractions? What do you need in common?

 

[boricua_2004]

a denominator if I am correct

 

[rocomath]

a denominator if I am correct

Yep. So a's denominator is just 1, so 1/b determines the denominator needed.

Multiply a's numerator and denominator by what number or letter?

 

[boricua_2004]

multiply by b

 

[rocomath]

multiply by b

So what do you get?

 

[boricua_2004]

b-a please tell me I am correct

 

[boricua_2004]

because if i multiply by b the b cancels in the denominator and then its a-b or b-a right

 

[rocomath]

because if i multiply by b the b cancels in the denominator and then its a-b or b-a right

No, you're only multiplying a by b and writing all of the numerator under a common denominator, b.

Ex:

1-\frac{1}{2}=1\cdot\frac{2}{2}-\frac{1}{2}=\frac{2-1}{2}

 

[boricua_2004]

so it should equal ab-1/b

 

[rocomath]

so it should equal ab-1/b

Be careful with how you write or type it.

Is that ab-\frac{1}{b} or \frac{ab-1}{b}?

 

[boricua_2004]

ab-1
b

 

[boricua_2004]

ab-1/b
the second one