This is a quadratic equation. There's a shortcut (two shortcuts really) called the Shakespeare Quadratic Formula (2b or -2b) applicable when the middle term is even:

$x^2 - 2bx + c \textrm{ has zeros } x= b\pm \sqrt{b^2-c}$

$ax^2 - 2bx + c \textrm{ has zeros } x= \dfrac 1 a( \left b\pm \sqrt{b^2-ac} \right)$

OK, our problem is

$9x^2 - 6x -7 = 0$

$x = \frac 1 9 (3 \pm \sqrt{9-(9)(-7)}) = \frac 1 9(3 \pm \sqrt{72})= \frac 1 9(3 \pm 3 \sqrt{8}) = \frac 1 3(1 \pm \sqrt 8)$

Typically we'd write $\sqrt 8 = 2 \sqrt 2$ but the answers here don't so we won't either.

Answer: C and D

7 0

3 years ago

What is 0.45 expressed as a decimal with a line over 5

antiseptic1488 [7]

Answer:

.45/5 converted to a decimal is 0.09

Step-by-step explanation:

I'm not sure what you mean by "with a line over 5" so I just thought u meant with 5 as the denominator

7 0

3 years ago

Can someone help me with this page

Ksju [112]

The first one is A. Number 2 is d. Number 3 is b because 20x20=400 and 21x21=441 and when you add them together you get 841 or 29x29. Number 4 is b because complementary angles are also right angles, they have to add up to 90 degrees. Number 5 is a because every angle is less than 90 degree. Number 6 is 30 because 60+90+x = 180 and when you solve for x you will get 30 degrees.

7 0

2 years ago

In a certain Algebra 2 class of 28 students, 23 of them play basketball and 12

erica [24]

Answer:

5/14

Step-by-step explanation:

P(A or B) = P(A) + P(B) − P(A and B)

25/28 = 23/28 + 12/28 − P(A and B)

P(A and B) = 10/28

P(A and B) = 5/14

3 0

3 years ago