Question

solve 4x^2-15x=3 how do i do that

Answer 1

sum = -15, and product = 4*3

Answer 2

write it as
4x^2 - 15x -3 = 0
check to see if this factorises first

Answer 3

quadratic formula

Answer 4

how did you figure that out?

Answer 5

yes - you can use quadratic formula - it does not factorise

Answer 6

[-b+-sqrt(b^2-4*a*c)]/(2*a)

Answer 7

used quadratic formula to solve for x: your given is a=4 b=-15 and c=-3

Answer 8

a=4 b=-15 c=-3

Answer 9

this is

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

for ax^2 + bx + c = 0

Answer 10

have you used this formula before jenni?

Answer 11

no it was a quiz and i have never used this before so i was wanting to know how to do it so next time i will get it right

Answer 12

i got (2x+5)(2x+3) as the simplified form is that what i am supposed to do

Answer 13

wait i meant factored form

Answer 14

ok well as chris said a=4 b=-15 and c=-3
so plugging these values into the formula

x = -(-15) + sqrt((-15)^2 - 4* 4*-3) / 2*4
= (15 + sqrt(273)) / 8 or ( 15 - sqrt(273)) / 8
this comes to 3.94 or -0.19
two roots

Answer 15

as what jimmy gave you a quadratic formula x =( -b +- sqrt(b^2 - 4ac)) / 2a
, just substitute all the given. a=4 b=-15 c=-3

Answer 16

ok im really confused

Answer 17

what? thats a different equation altogether

Answer 18

2x+5)(2x+3) = 0 right?

Answer 19

the simplest way to solve is by using the quadratic formula"-)

Answer 20

(2x-5)(2x+3) was what i factored out 4x^2-15-3=0

Answer 21

no those are the factors of 4x^2 -4x -15
(2x+5)(2x+3) = 4x^2 + 16x + 15

Answer 22

the equation you originally posted cant be factored that why we used the formula

Answer 23

anyway - i must go

Answer 24

The quadratic formula is:\[-b \pm \sqrt{b ^{2}-4ac}\over 2a\]
In the case of the original formula 4x^2-15x=3, it would be rewritten to standard form giving you \[4x ^{2}-15x-3=0\] where a=4,b=-15, and c=-3

Answer 25

Plug those vales into the quadratic formula and you will get the roots of the equation.

Answer 26

\[15\pm \sqrt{15^{2}+48}\over 8\] Can you take it from there?

Answer 27

\[15\pm \sqrt{273}\over8\]
\[15\pm16.522712 \over 8\]

Answer 28

3.94, -0.19