Posted by **Hokoslavia** on Sunday, March 9, 2008 at 1:17pm.

use the quadratic formula to solve the equation

4x^2-7x-2=0

- algebra -
**drwls**, Sunday, March 9, 2008 at 1:54pm
Your equation is already in the form ax^2 + bx + c = 0

In your case,

a = 4, b = -7 and c = -2.

The quadratic formula for the solution values of x, which you should memorize or learn to derive, is

x = [-b +/- sqrt (b^2-4ac)]/2a

It would good practice for you to do the final alculation yourself

b^2-4ac = 81 in this case, and has a square root that is an integer, making the answer rather easy to write down.

- algebra -
**Damon**, Sunday, March 9, 2008 at 1:54pm
x = -b/2a +/- (1/2a)sqrt(b^2 - 4 a c)

a = 4

b = -7

c = -2

x = 7/8 +/- (1/8) sqrt ( 49 + 32)

x = 7/8 +/- (1/8) sqrt (81)

lucky (9*9)=81

so

x = 7/8 +/- 9/8

x = 16/8 or -2/8 wow, nice polite numbers

so

x = 2 or - 1/4

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