According to the secant-tangent theorem, we have the following expression:
Now, we solve for <em>x</em>.
Then, we use the quadratic formula:
![x_{1,2}=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}](https://tex.z-dn.net/?f=x_%7B1%2C2%7D%3D%5Cfrac%7B-b%5Cpm%5Csqrt%5B%5D%7Bb%5E2-4ac%7D%7D%7B2a%7D)
Where a = 1, b = 6, and c = -315.
![\begin{gathered} x_{1,2}=\frac{-6\pm\sqrt[]{6^2-4\cdot1\cdot(-315)}}{2\cdot1} \\ x_{1,2}=\frac{-6\pm\sqrt[]{36+1260}}{2}=\frac{-6\pm\sqrt[]{1296}}{2} \\ x_{1,2}=\frac{-6\pm36}{2} \\ x_1=\frac{-6+36}{2}=\frac{30}{2}=15 \\ x_2=\frac{-6-36}{2}=\frac{-42}{2}=-21 \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20x_%7B1%2C2%7D%3D%5Cfrac%7B-6%5Cpm%5Csqrt%5B%5D%7B6%5E2-4%5Ccdot1%5Ccdot%28-315%29%7D%7D%7B2%5Ccdot1%7D%20%5C%5C%20x_%7B1%2C2%7D%3D%5Cfrac%7B-6%5Cpm%5Csqrt%5B%5D%7B36%2B1260%7D%7D%7B2%7D%3D%5Cfrac%7B-6%5Cpm%5Csqrt%5B%5D%7B1296%7D%7D%7B2%7D%20%5C%5C%20x_%7B1%2C2%7D%3D%5Cfrac%7B-6%5Cpm36%7D%7B2%7D%20%5C%5C%20x_1%3D%5Cfrac%7B-6%2B36%7D%7B2%7D%3D%5Cfrac%7B30%7D%7B2%7D%3D15%20%5C%5C%20x_2%3D%5Cfrac%7B-6-36%7D%7B2%7D%3D%5Cfrac%7B-42%7D%7B2%7D%3D-21%20%5Cend%7Bgathered%7D)
<h2>Hence, the answer is 15 because lengths can't be negative.</h2>
4) You know slope-intercept form is y=mx+b. So using these two given points, you can find the slope!
(-8,5) (-3,10) [Use the y1-y2 over x1-x2 formula to solve for slope]
10 - 5 5
--------- = ----- = 1
-3-(-8) 5
Hurray! You got a slope of one. Now substitute this back into your original equation:
y=mx+b --> y=1x+b
Next, we find what our "b" is, or what our y-intercept is:
Using one of the previous points given, substitute them into the new equation:
[I used the point (-3, 10) ]
y=1x+b
10=1(-3)+b SUBSTITUTE
10=-3+b MULTIPLY
10=-3+b
+3 +3 ADD
----------
13=b SIMPLIFY
So, now we have our y-intercept. Use this and plug it into the equation:
y=1x+b --> y=1x+13
y=1x+13 is our final answer.
5) So for perpendicular lines, your slope will be the opposite reciprocal of the original slope. (Ex: Slope is 2, but perpendicular slope is -1/2)
We have the equation y= 3x-1, so find the reciprocal slope!
--> y=-1/3x-1
Good! Now we take our given point, (9, -4) and plug it into the new equation:
y=-1/3x-1
-4=-1/3(9)+b SUBSTITUTE and revert "-1" to "b", for we are trying to find the y- -4=-3+b intercept of our perpendicular equation.
+3 +3 ADD
--------
-1=b SIMPLIFY
So, our final answer is y=-1/3x+(-1)
6) I don't know, sorry! :(
I think that the answer is 2, because if you multiply two by each factor in the original photograph then you get the size of the new photograph.
