✔ 最佳答案
Read the Steps and then follow the work.
ax^2 + bx + c = 0
1. Multiply a by c
2. Find numbers that multiply to ac and add/subtract to b (in your case we will subtract since the last sign in minus)
3. Rewrite b using the two numbers you found in step 2 (in your case one number needs to be positive and one negative, and since the first sign is positive the larger number needs to be positive)
4. Group the first two terms together, and group the last two terms together
5. Factor out the greatest common factor for each grouping (after you do this what is in the parenthesis shoudl be the same)
6. Make two new sets of parenthesis, the numbers outside each grouping go in one set, and the numbers inside each grouping go in the other set)
7. FOIL to get check your work.
3x^2 + 4x - 4 = 0
3(4) = 12 So we want number that mult to 12 and subtract to 4
6 (2) = 12 and 6-2 = 4
So now we rewrite replacing the middle term using 6 and 4
3x^2 - 2x + 6x - 4 = 0
Group the first two and the last two terms
(3x^2 - 2x) + (6x - 4) = 0
Now factor out the GCF of each group.
x(3x - 2) + 2(3x - 2) = 0
Now two new sets of parenthesis.
(x + 2)(3x - 2) = 0
Don't forget to FOIL to make sure your answer is correct
(x + 2)(3x - 2) = 0
3x^2 - 2x + 6x - 4 = 0
3x^2 + 4x - 4 = 0
If you want to solve for x you set each set of parenthsis = to 0
x + 2 = 0
x = -2
3x - 2 = 0
3x = 2
x = 2/3