how to work the problem step by step using quadratic formula

Question

x²+3x-7=0

Answer 1

First you need to remember the quadratic formula.

You can learn it as a song.  "Do you know Pop Goes the Weasel"?

 

ex equals negative bee

plus or minus the square root

of bee squared minus four a see

all over two a

 

Now remember the standard form of a quadratic equation

Ax² + Bx + C = 0

 

Now decide what A, B, and C are and plug them into the formula.

For this example A = 1, B = 3, and C = -7

 

x= -B ± √ (B² - 4AC)

             2A

 

= -3 ± √ (3² - 4•1•-7)

            2•1

 

= -3 ± √ (9-(28))

           2

 

= -3 ± √(37)

           2

 

= -3 ± 6.08

           2

 

= -1.5 ±  3.04

 

= 4.54 and -1.54

 

You can do your other problem the same way.

Try it on your own.  Let us know if you get stuck.

Answer 2

x² + 3x - 7 = 0 it's in the form ax² + bx + c = 0

 

so, we have a=1, b = 3, c = -7

 

the quadratic equation is:

 

[-b ± √(b² - 4ac)]/2a

 

so,

 

[-3 ± √(9 - 4*1*-7)]/2(1)

 

[-3 ± √37]/2