Help Me WITH ALGEBRA

label Algebra
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1. Calculate the discriminant.

x2 + 2x – 2 = 0

 –8

 –4

 8

 12

2. What number would you have to add to both sides to complete the square?

 x2 + 12x = –6

144

 36

 –36

–144

3. Solve by using the perfect squares method.

x2 – 12x + 36 = 0

–18

 –6

 6

18

5. Lijuan is solving the equation x2 – x = 14 with the quadratic formula. What values should she use for a, b, and c?

a = –1, b = 1, c = –14

a = 1, b = –1, c = –14

a = –1, b = 1, c = 14

a = 1, b = –1, c = 14

May 13th, 2015

Question 1.

The discriminant is equal to b^2-4ac where the equation is of the form ax^2+bx+c=0. In this question, a=1, b=2 and c=-2. Therefore, the discriminant is equal to (2^2)-(4*1*-2)=4-(-8)=12

Question 2.

Completing the square on the left gives (x+6)^2 which when expanded gives x^2+12x+36. Therefore we must take away the 36 from each side to be left with just x^2+12x on the left. Therefore, the answer is -36.

Question 3.

We have the equation x^2-12x+36=0. First we look at the 'c' value which is 36 and think which number we can square to find it. In this case it is either 6 or -6. Trying each gives (x-6)^2=x^2-12x+36 and (x+6)^2=x^2+12x+36. We can see here the (x-6)^2 is the correct factorization of the left hand side. Therefore, we now have the equation (x-6)^2=0. For this to be true, the bracket must equal 0 and so x must equal 6. Therefore, the answer is 6.

Question 5.

We have the equation x^2-x=14. We must rearrange this equation so we have 0 on the right hand side. To do this we must subtract 14 from each side. This gives x^2-x-14=0. Once again, the equation is of the form ax^2+bx+c=0 and so we see that here, a=1, b=-1 and c=-14.

May 13th, 2015

um can u highlight plz

May 13th, 2015

What would you like me to highlight?

May 13th, 2015

the answers plz

May 13th, 2015

1: Answer is 12.

2: Answer is -36.

3: Answer is 6

4: Answer is the second one down: a=1, b=-1, c=-14

May 13th, 2015

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