\(\text{use the quadratic formula :} \\x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)
here is the roots:
http://www.cymath.com/answer.php?q=2x%5E2-8x%2B7%3D0
\(176-96=80\\ 96:80\\ 6:5\)
Answer: 6:5
2099.8
0
\(32 = 2(k – 34)\\ \frac{32}{2}=\frac{2(k-34)}{2}\\ 16=k-34 \\ \text{add to both sides 34: }\\ 16+34=k-34+34\\ 50=k\)
\(2(a^2-25)=21a\\ a^2-25=10.5a\\ a^2-10.5a-25=0\)
Do the rest by yourself then write the answer
http://www.cymath.com/answer.php?q=a^2-10.5a-25%3D0
\(w=\frac{7}{8},-\frac{7}{8}\)
there is two unknowns
Here is the graph:
https://www.desmos.com/calculator/dsl83ietui
\(13^2-3^2=x^2\\ x=\sqrt{160}=12.6491106406735173\)
Answer: 12.6