8x^2-7x-4=0

Simple and best practice solution for 8x^2-7x-4=0 equation. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so don`t hesitate to use it as a solution of your homework.

If it's not what You are looking for type in the equation solver your own equation and let us solve it.

Solution for 8x^2-7x-4=0 equation:


Simplifying
8x2 + -7x + -4 = 0

Reorder the terms:
-4 + -7x + 8x2 = 0

Solving
-4 + -7x + 8x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
8 the coefficient of the squared term: 

Divide each side by '8'.
-0.5 + -0.875x + x2 = 0

Move the constant term to the right:

Add '0.5' to each side of the equation.
-0.5 + -0.875x + 0.5 + x2 = 0 + 0.5

Reorder the terms:
-0.5 + 0.5 + -0.875x + x2 = 0 + 0.5

Combine like terms: -0.5 + 0.5 = 0.0
0.0 + -0.875x + x2 = 0 + 0.5
-0.875x + x2 = 0 + 0.5

Combine like terms: 0 + 0.5 = 0.5
-0.875x + x2 = 0.5

The x term is -0.875x.  Take half its coefficient (-0.4375).
Square it (0.19140625) and add it to both sides.

Add '0.19140625' to each side of the equation.
-0.875x + 0.19140625 + x2 = 0.5 + 0.19140625

Reorder the terms:
0.19140625 + -0.875x + x2 = 0.5 + 0.19140625

Combine like terms: 0.5 + 0.19140625 = 0.69140625
0.19140625 + -0.875x + x2 = 0.69140625

Factor a perfect square on the left side:
(x + -0.4375)(x + -0.4375) = 0.69140625

Calculate the square root of the right side: 0.831508418

Break this problem into two subproblems by setting 
(x + -0.4375) equal to 0.831508418 and -0.831508418.

Subproblem 1

x + -0.4375 = 0.831508418 Simplifying x + -0.4375 = 0.831508418 Reorder the terms: -0.4375 + x = 0.831508418 Solving -0.4375 + x = 0.831508418 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.4375' to each side of the equation. -0.4375 + 0.4375 + x = 0.831508418 + 0.4375 Combine like terms: -0.4375 + 0.4375 = 0.0000 0.0000 + x = 0.831508418 + 0.4375 x = 0.831508418 + 0.4375 Combine like terms: 0.831508418 + 0.4375 = 1.269008418 x = 1.269008418 Simplifying x = 1.269008418

Subproblem 2

x + -0.4375 = -0.831508418 Simplifying x + -0.4375 = -0.831508418 Reorder the terms: -0.4375 + x = -0.831508418 Solving -0.4375 + x = -0.831508418 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.4375' to each side of the equation. -0.4375 + 0.4375 + x = -0.831508418 + 0.4375 Combine like terms: -0.4375 + 0.4375 = 0.0000 0.0000 + x = -0.831508418 + 0.4375 x = -0.831508418 + 0.4375 Combine like terms: -0.831508418 + 0.4375 = -0.394008418 x = -0.394008418 Simplifying x = -0.394008418

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.269008418, -0.394008418}

See similar equations:

| 10C-11=5C+39 | | 3e+19=-19 | | 4z+5=9z-27 | | 8(y+2)=-16 | | 15x^2-10x-18xy+12y=0 | | 3X+9=X-21 | | -30=y/4 | | 2w+11=7w+41 | | 40=7d-9 | | 3y+4y=63 | | 11x-13=2x-5 | | 5d+16+d=40 | | 36x^2-1/25=0 | | x^2+y^3-4x+2y=b | | 8x+11=4x-5 | | x^2+28x-9=0 | | 25.6=8y | | 3x^2=12+9x | | u/8.75=7 | | 2-x=160 | | 5x-18x=3x+2 | | 6(n+4)=0 | | x=76.5+4.59 | | -8+x=19 | | b^3-9b^2-24b+9=0 | | -3=4m-8 | | x-(8)=3 | | x=.765(100)+.06(76.5)(100) | | -4+x=-12 | | (x^2+9)=289 | | 7=-4+b | | x=.765(100)+.06(.765)(100) |

Equations solver categories