Answer:
D
Step-by-step explanation:
1. 3x² + 12x - 15 = 0
x = <u>-(12) +/- √((12)² - 4(3)(-15))</u>
2(3)
x = <u>-12 +/- √(144 + 180)</u>
6
x = <u>-12 +/- √(324)
</u> 6<u>
</u> x = <u>-12 +/- 18 </u>
6
x = -2 <u>+</u> 3
x = -2 + 3 x = -2 - 3
x = 1 x = -5
--------------------------------------------------------------------------------------------
2. 5x² + 11x + 2 = 0
x = <u>-(11) +/- √((11)² - 4(5)(2))</u>
2(5)
x = <u>-11 +/- √(121 - 40)</u>
10
x = <u>-11 +/- √(81)
</u> 10
x = <u>-11 +/- 9</u>
10
x = -1¹/₁₀ <u>+</u> ⁹/₁₀
x = -1¹/₁₀ + ⁹/₁₀ x = -1¹/₁₀ - ⁹/₁₀
x = ¹/₅ x = -2
--------------------------------------------------------------------------------------------
3. 2x² - 11x + 14 = 0
x = <u>-(-11) +/- √((-11)² - 4(2)(14))</u>
2(3)
x = <u>11 +/- √(121 - 102)</u>
6
x = <u>11 +/- √(9)</u>
6
x = <u>11 +/- 3</u>
6
x = 1⁵/₆ <u>+</u> ¹/₂
x = 1⁵/₆ + ¹/₂ x = 1⁵/₆ - ¹/₂
x = 2¹/₃ x = 1¹/₃
--------------------------------------------------------------------------------------------
4. 2x² - x - 15 = 0
x = <u>-(-1) +/- √((-1)² - 4(2)(-15))</u>
2(2)
x = <u>1 +/- √(1 + 120)</u>
4
x = <u>1 +/- √(121)</u>
4
x = <u>1 +/- 11</u>
4
x = ¹/₄ <u>+</u> 2³/₄
x = ¹/₄ + 2³/₄ x = ¹/₄ - 2³/₄
x = 3 x = 2¹/₂
<u />
Lets write as an equation the info provided in the problem:
original area = 200*300 = 60000 squared meters
Adding x meters to the length is: 300 + x
Adding x meters to the width is: 200 + x
If the area doubles in size we have: 2*<span>60000
Now writing as a single equation all info:
(300 + x)(200 + x) = 120000
We have to make the operations and solve:
60000 + 300x + 200x + x^2 = </span><span>120000
x^2 + 500x - 60000 = 0
This is a squared trinomial, to solve it we need two numbers that subtracted give us 500 and multiplied -60000:
(x + 600)(x -100) = 0
So there are two solutions, x = -600 and x = 100, we choose the positive one:
x = 100
thererefore the value of x is 100 meters</span>
Answer:
there are 45 people in the group
2/3xA=30
2A=30x3
A=90/2
A=45
Hi there!
First we need to remember the following.
Now substitute both of the formulas.
Work out the parenthesis.
And finally collect terms.
~ Hope this helps you!
