Math  /  Algebra

QuestionSolve using the quadratic formula. 2t2+9t+7=0-2 t^{2}+9 t+7=0
Write your answers as integers, proper or improper fractions in simplest form, or decimals rounded to the nearest hundredth. t=t= \square or t=t= \square

Studdy Solution

STEP 1

What is this asking? We need to find the values of tt that make this equation true: 2t2+9t+7=0-2t^2 + 9t + 7 = 0. Watch out! Remember, the quadratic formula has a plus-or-minus sign, so we'll get two answers!
Also, be careful with those negative signs when plugging into the formula.

STEP 2

1. Set up the Quadratic Formula
2. Plug in the values
3. Simplify the Expression
4. Calculate the two solutions

STEP 3

Alright, let's **kick things off** with the **star of the show**, the **quadratic formula**!
It helps us solve equations that look like ax2+bx+c=0ax^2 + bx + c = 0.
The formula is:
x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

STEP 4

Remember, aa, bb, and cc are just the numbers in front of the x2x^2, xx, and the constant term, respectively.

STEP 5

In our equation, 2t2+9t+7=0-2t^2 + 9t + 7 = 0, we can see that a=2a = -2, b=9b = 9, and c=7c = 7.
Let's **plug these bad boys** into the quadratic formula!
t=9±924(2)72(2)t = \frac{-9 \pm \sqrt{9^2 - 4 \cdot (-2) \cdot 7}}{2 \cdot (-2)}

STEP 6

Now, let's **clean this up**!
First, we'll tackle the inside of the square root: 929^2 is 8181, and 4(2)74 \cdot (-2) \cdot 7 is 56-56.
So, inside the square root, we have 81(56)81 - (-56), which is the same as 81+56=13781 + 56 = 137.
t=9±1374t = \frac{-9 \pm \sqrt{137}}{-4}

STEP 7

We can rewrite this as two separate solutions:
t=9+1374ort=91374t = \frac{-9 + \sqrt{137}}{-4} \quad \text{or} \quad t = \frac{-9 - \sqrt{137}}{-4}

STEP 8

Let's multiply the numerator and denominator by 1-1 to make the denominator positive.
Remember, multiplying by 11\frac{-1}{-1} is the same as multiplying by 11, so it doesn't change the value of the expression.
t=91374ort=9+1374t = \frac{9 - \sqrt{137}}{4} \quad \text{or} \quad t = \frac{9 + \sqrt{137}}{4}

STEP 9

Since 13711.70\sqrt{137} \approx 11.70, we can approximate our solutions:
t911.704ort9+11.704t \approx \frac{9 - 11.70}{4} \quad \text{or} \quad t \approx \frac{9 + 11.70}{4}t2.704ort20.704t \approx \frac{-2.70}{4} \quad \text{or} \quad t \approx \frac{20.70}{4}t0.68ort5.18t \approx -0.68 \quad \text{or} \quad t \approx 5.18

STEP 10

t0.68t \approx -0.68 or t5.18t \approx 5.18

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