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Example: 5𝑥 2 = 25
𝑥2 = 5
(divide both sides by 5)
(take the square root of both sides)
𝑥 = √5 𝑎𝑛𝑑 − √5
So, you solve for the x-intercepts by getting x by itself. Remember, when you take the square
root of a number (ex. √5 above) the answer is both the positive and negative value of that
answer, hence why I got 2 answers in my example above.
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How to find the max/min:
x-value =
−𝑏
2𝑎
and y-value = plug x-value into equation and solve for y.
Example: 𝑦 = 2𝑥 2 + 5
x-value =
−(0)
2(2)
0
=4=0
y-value = 𝑦 = 2(0)2 + 5 = 5
So, 𝑀𝑖𝑛𝑖𝑚𝑢𝑚 = (0,5)
Example: 𝑦 = 3𝑥 2 − 2𝑥
x-value =
−(−2)
2(3)
2
1
=6=3
1 2
1
1
2
3
2
1
2
1
y-value = 𝑦 = 3 (3) − 2 (3) = 3 (9) − 3 = 9 − 3 = 3 − 3 = − 3
1 −1
So, 𝑀𝑖𝑛𝑖𝑚𝑢𝑚 = (3 ,
3
)
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