Tuesday

March 3, 2015

March 3, 2015

Posted by **Heather** on Monday, August 4, 2014 at 10:48pm.

The answer choices are:

(A) 8a^2 + 6

(B) 8a^2 + 12

(C) 12a^2 + 6

(D) 18a^2 + 6

(E) 18a^2 + 12

Thank you!

- Math -
**Heather**, Monday, August 4, 2014 at 10:57pmActually, just did it again and got (D). However, it's an SAT question and I need the fastest way to solve it... what I did was plug in values for a and b (3 and 2, respectively) then find c (78) and plug a (3) back into each of the choices to see if c (78) and the answer were equal. Is there a faster way to do it?

- Math -
**Steve**, Monday, August 4, 2014 at 11:17pmStart substituting:

1/3c = 6b^2, so

c = 18b^2

Now, 3b=2a, so

18b^2 = 2(3b)^2 = 2(2a)^2 = 8a^2

I think you left out a +6 somewhere, since there are no such terms shown.

Also, if a=3 and b=2, c=72, not 78, so it's a good sign something has been left out.

So, if D is the answer, the question has been garbled. At any rate, you can see how I did it, so maybe you can apply the logic to the correct problem.

- Math -
**Heather**, Monday, August 4, 2014 at 11:43pmSorry- it was 1/3c = 6b^2 + 2.

I can see your way of substituting, though!

**Answer this Question**

**Related Questions**

Math - Describe the steps for simplifying the expression 3a^3 + 4 - 4a - 2a^3 + ...

math - Hi I need help with 5 questions..some of it is confusing to me. I just ...

algebra - simplify -2a^+6ab^-12a^b/-24ab the b -12a^b the b is to the third ...

math - Look at this trinomial 32a^4 + 18a^3 - 12a Write the polynomial as the ...

Math - (6q^6)^-4 When I worked this I got 1/1296q^24. One of the choices given ...

Math Algebra Multiply - (a+3)^3 is answer: 3a+9a+9 12a+9

algebra - simplify 2a^2 + 6ab^2-12a^2b^3 divided by 24ab -2a^2/-24ab + 6ab^2/...

math - subtract: express your answer in simplest form. 5x-3/6 - (x+3)/6 answer ...

Statistics - Over time, a student analyzes her ability to guess correctly after ...

pre alg - 12a^-4 b^6 c^-3 / 30 a^2 b^-5 c^-3 is the answer 2b/5a^6 c^?