Answer: a) x = {-3, 3, -3i, 3i}
b) x = {-√5, √5}
c) x = {-√3, √3, -i√2, i√2}
<u>Step-by-step explanation:</u>
![a)\ x^4-81=0\\\\(x^2-9)(x^2+9)=0\\\\x^2=9\quad and\quad x^2=-9\\\\x=\pm 3\quad and\quad x=\pm3i](https://tex.z-dn.net/?f=a%29%5C%20x%5E4-81%3D0%5C%5C%5C%5C%28x%5E2-9%29%28x%5E2%2B9%29%3D0%5C%5C%5C%5Cx%5E2%3D9%5Cquad%20and%5Cquad%20x%5E2%3D-9%5C%5C%5C%5Cx%3D%5Cpm%203%5Cquad%20and%5Cquad%20x%3D%5Cpm3i)
![b)\ x^4+10x^2+25=0\\\\(x^2+5)^2=0\\\\x^2=-5\\\\x=\pm i\sqrt5](https://tex.z-dn.net/?f=b%29%5C%20x%5E4%2B10x%5E2%2B25%3D0%5C%5C%5C%5C%28x%5E2%2B5%29%5E2%3D0%5C%5C%5C%5Cx%5E2%3D-5%5C%5C%5C%5Cx%3D%5Cpm%20i%5Csqrt5)
![c)\ x^4-x^2-6=0\\\\(x^2-3)(x^2+2)=0\\\\x^2-3=0\quad and\quad x^2+2=0\\\\x^2=3\qquad and\quad x^2=-2\\\\x=\pm\sqrt3\quad and\quad x=\pm i\sqrt2](https://tex.z-dn.net/?f=c%29%5C%20x%5E4-x%5E2-6%3D0%5C%5C%5C%5C%28x%5E2-3%29%28x%5E2%2B2%29%3D0%5C%5C%5C%5Cx%5E2-3%3D0%5Cquad%20and%5Cquad%20x%5E2%2B2%3D0%5C%5C%5C%5Cx%5E2%3D3%5Cqquad%20and%5Cquad%20x%5E2%3D-2%5C%5C%5C%5Cx%3D%5Cpm%5Csqrt3%5Cquad%20and%5Cquad%20x%3D%5Cpm%20i%5Csqrt2)
Answer:
28
Step-by-step explanation:
Givens
Game 1: 30
Game 2: 18
Game 3: 28
Game 4: x
Solution
(30 + 18 + 28 + x) / 4 = 26 Multiply both sides by 4
4* (30 + 18 + 28 + x) / 4 = 26 * 4 The 4s on the left cancel
30 + 18 + 28 + x = 104 Add the 3 other numbers together
76 + x = 104 Subtract 76 from both sides.
76-76+x = 104-76 The 76s on the left disappear.
x = 28
Answer
in the next game he must score 28 points to average 26
10.50 x 0.2 = $2.10
Therefore, 20% of $10.50 is $2.10
With 20% off, the book will cost
10.50-2.10 = $8.40
3+1=4
4/2=2
2x1=2
Answer: 2in^2
99+101+100=300 is an answer