2r^2-7r-16=0

Simple and best practice solution for 2r^2-7r-16=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 2r^2-7r-16=0 equation:


Simplifying
2r2 + -7r + -16 = 0

Reorder the terms:
-16 + -7r + 2r2 = 0

Solving
-16 + -7r + 2r2 = 0

Solving for variable 'r'.

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

Divide each side by '2'.
-8 + -3.5r + r2 = 0

Move the constant term to the right:

Add '8' to each side of the equation.
-8 + -3.5r + 8 + r2 = 0 + 8

Reorder the terms:
-8 + 8 + -3.5r + r2 = 0 + 8

Combine like terms: -8 + 8 = 0
0 + -3.5r + r2 = 0 + 8
-3.5r + r2 = 0 + 8

Combine like terms: 0 + 8 = 8
-3.5r + r2 = 8

The r term is -3.5r.  Take half its coefficient (-1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
-3.5r + 3.0625 + r2 = 8 + 3.0625

Reorder the terms:
3.0625 + -3.5r + r2 = 8 + 3.0625

Combine like terms: 8 + 3.0625 = 11.0625
3.0625 + -3.5r + r2 = 11.0625

Factor a perfect square on the left side:
(r + -1.75)(r + -1.75) = 11.0625

Calculate the square root of the right side: 3.326033674

Break this problem into two subproblems by setting 
(r + -1.75) equal to 3.326033674 and -3.326033674.

Subproblem 1

r + -1.75 = 3.326033674 Simplifying r + -1.75 = 3.326033674 Reorder the terms: -1.75 + r = 3.326033674 Solving -1.75 + r = 3.326033674 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1.75' to each side of the equation. -1.75 + 1.75 + r = 3.326033674 + 1.75 Combine like terms: -1.75 + 1.75 = 0.00 0.00 + r = 3.326033674 + 1.75 r = 3.326033674 + 1.75 Combine like terms: 3.326033674 + 1.75 = 5.076033674 r = 5.076033674 Simplifying r = 5.076033674

Subproblem 2

r + -1.75 = -3.326033674 Simplifying r + -1.75 = -3.326033674 Reorder the terms: -1.75 + r = -3.326033674 Solving -1.75 + r = -3.326033674 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '1.75' to each side of the equation. -1.75 + 1.75 + r = -3.326033674 + 1.75 Combine like terms: -1.75 + 1.75 = 0.00 0.00 + r = -3.326033674 + 1.75 r = -3.326033674 + 1.75 Combine like terms: -3.326033674 + 1.75 = -1.576033674 r = -1.576033674 Simplifying r = -1.576033674

Solution

The solution to the problem is based on the solutions from the subproblems. r = {5.076033674, -1.576033674}

See similar equations:

| -7(-8k+1)=-343 | | 3x+3(-6x+12)=186 | | 14=5x-6 | | 2x^2-7r-16=0 | | 8=x/-5+5 | | 6n+21=4n+57+2n | | Ln(n^2+12)=ln(-9n-2) | | 3k-6+2k=12+8k-33 | | -4x-18=-(4x+2) | | 3/2+3/4 | | 8+4y=12 | | 65x=55x+100 | | m-14/9=-27 | | 4k+11+2k=-5-27k-3 | | 4x+16=4(x+4) | | 11/2+3/4 | | 3=-6n-9 | | 3(4-x)-22=x+48 | | 99x^8+63x^5-45x^2= | | -3+4(-6y-2)=4(2y-1)+3 | | y-10=-1(x-4) | | -25y+25y=-(22y+15)+10+22 | | 3x-10=5x+14 | | -33k=19 | | B+(-11)=6 | | x/3+7=11 | | -2*(-8)+4y=-8 | | -12(m-4)=240 | | -2m+8=4 | | -1v-6= | | 3x(4x+5)-5(4x+5)=0 | | (5x-2)-(6-2X)=-x-9+5x |

Equations solver categories