One solution of 21x^2 + bx -4 = 0 is -4/3. find b and the other solution.

see explanation

Step-by-step explanation:

Given that x = - is a solution of the equation, then

Substitute this value into the equation and solve for b

21 (- )² + b (- ) - 4 = 0

21 × - b - 4 = 0

- b - 4 = 0

Multiply through by 3

112 - 4b - 12 = 0

100 - 4b = 0 ( subtract 100 from both sides )

- 4b = - 100 ( divide both sides by - 4 )

b = 25 ← value of b

The equation can now be written as

21x² + 25x - 4 = 0 ← in standard form

with a = 21, b = 25, c = - 4

Use the quadratic formula to solve for x

x = ( - 25 ± ) / 42

  = ( - 25 ± ) / 42

  = ( - 25 ± 31 ) / 42

x = = = -

or x = =   =

The other solution is x =

6,250

step-by-step explanation:

to get the area, multiply 360 by 160.(57,600)

to find out how many bags of fertilizer it will take, first figure out how many square feet one bag can hold. divide 1000 by 8(125) to get the unit rate(how many square feet one pound of fertilizer can hold)and multiply it by 50(6250). if i haven't made a mistake, that is the answer.