Item 8 Solve for x. Use the quadratic formula. 2x2−5x−9=0 Enter the solutions, in simplified radical form, in the boxes.

Mathematics

2 answers:

Lubov Fominskaja [6]3 years ago

7 0

Answer:

5+√97/4

Also 5-√97/4

Step-by-step explanation:

The Quadratic formula is x=-b+-√b^2-4ac/2a

This means that we should plug the values for A B AND C into the formula

We can work out that

A = 2

B=-5

C=-9

Once we have put these into the formula we get

5+√97/4 (all over 4) aka 3.71

Also 5-√97/4 (all over 4) aka -1.21

Dimas [21]3 years ago

3 0

Answer:

$\large\boxed{x=\dfrac{5-\sqrt{97}}{4}\ or\ x=\dfrac{5+\sqrt{97}}{4}}$

Step-by-step explanation:

$\text{Let}\ ax^2+bx+c=0\\\\\text{The quadratic formula:}\\\\\Delta=b^2-4ac\\\\\text{If}\ \Delta>0,\ \text{then the equation has two solutions}\ x=\dfrac{-b\pm\sqrt\Delta}{2a}\\\\\text{If}\ \Delta=0,\ \text{then the equation has one solution}\ x=\dfrac{-b}{2a}\\\\\text{If}\ \Delta$

$\text{The equation}\ 2x^2-5x-9=0\\\\a=2,\ b=-5,\ c=-9\\\\\Delta=(-5)^2-4(2)(-9)=25+72=97>0\\\\\sqrt\Delta=\sqrt{97}\\\\x_1=\dfrac{-(-5)-\sqrt{97}}{2(2)}=\dfrac{5-\sqrt{97}}{4}\\\\x_2=\dfrac{-(-5)+\sqrt{97}}{2(2)}=\dfrac{5+\sqrt{97}}{4}$

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The formula A equals =P left parenthesis 1 plus r right parenthesis squared (1+r)2 gives the amount A in dollars that P dollars

vlabodo [156]

The interest rate is 3.5%.

EXPLANATION

We substitute the given values into the formula;

$A=P(1+\frac{r}{100})^t$

to obtain

$6427.35=6000(1+\frac{r}{100})^2$

We divide through by 6000 to obtain,

$\frac{6427.35}{6000}=(1+\frac{r}{100})^2$

This implies that,

$1.071225=(1+\frac{r}{100})^2$

We take the square root of both sides,

$\sqrt{1.071225}=(1+\frac{r}{100})$

This gives us,

$1.035=(1+\frac{r}{100})$

Add -1 to both sides of the equation to obtain

$0.035=\frac{r}{100}$

Multiply through by 100 to obtain;

$r=3.5$ %

$Therefore the rate is 3.5%$