3m^2-5m-21=0

Simple and best practice solution for 3m^2-5m-21=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 3m^2-5m-21=0 equation:


Simplifying
3m2 + -5m + -21 = 0

Reorder the terms:
-21 + -5m + 3m2 = 0

Solving
-21 + -5m + 3m2 = 0

Solving for variable 'm'.

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

Divide each side by '3'.
-7 + -1.666666667m + m2 = 0

Move the constant term to the right:

Add '7' to each side of the equation.
-7 + -1.666666667m + 7 + m2 = 0 + 7

Reorder the terms:
-7 + 7 + -1.666666667m + m2 = 0 + 7

Combine like terms: -7 + 7 = 0
0 + -1.666666667m + m2 = 0 + 7
-1.666666667m + m2 = 0 + 7

Combine like terms: 0 + 7 = 7
-1.666666667m + m2 = 7

The m term is -1.666666667m.  Take half its coefficient (-0.8333333335).
Square it (0.6944444447) and add it to both sides.

Add '0.6944444447' to each side of the equation.
-1.666666667m + 0.6944444447 + m2 = 7 + 0.6944444447

Reorder the terms:
0.6944444447 + -1.666666667m + m2 = 7 + 0.6944444447

Combine like terms: 7 + 0.6944444447 = 7.6944444447
0.6944444447 + -1.666666667m + m2 = 7.6944444447

Factor a perfect square on the left side:
(m + -0.8333333335)(m + -0.8333333335) = 7.6944444447

Calculate the square root of the right side: 2.773886163

Break this problem into two subproblems by setting 
(m + -0.8333333335) equal to 2.773886163 and -2.773886163.

Subproblem 1

m + -0.8333333335 = 2.773886163 Simplifying m + -0.8333333335 = 2.773886163 Reorder the terms: -0.8333333335 + m = 2.773886163 Solving -0.8333333335 + m = 2.773886163 Solving for variable 'm'. Move all terms containing m to the left, all other terms to the right. Add '0.8333333335' to each side of the equation. -0.8333333335 + 0.8333333335 + m = 2.773886163 + 0.8333333335 Combine like terms: -0.8333333335 + 0.8333333335 = 0.0000000000 0.0000000000 + m = 2.773886163 + 0.8333333335 m = 2.773886163 + 0.8333333335 Combine like terms: 2.773886163 + 0.8333333335 = 3.6072194965 m = 3.6072194965 Simplifying m = 3.6072194965

Subproblem 2

m + -0.8333333335 = -2.773886163 Simplifying m + -0.8333333335 = -2.773886163 Reorder the terms: -0.8333333335 + m = -2.773886163 Solving -0.8333333335 + m = -2.773886163 Solving for variable 'm'. Move all terms containing m to the left, all other terms to the right. Add '0.8333333335' to each side of the equation. -0.8333333335 + 0.8333333335 + m = -2.773886163 + 0.8333333335 Combine like terms: -0.8333333335 + 0.8333333335 = 0.0000000000 0.0000000000 + m = -2.773886163 + 0.8333333335 m = -2.773886163 + 0.8333333335 Combine like terms: -2.773886163 + 0.8333333335 = -1.9405528295 m = -1.9405528295 Simplifying m = -1.9405528295

Solution

The solution to the problem is based on the solutions from the subproblems. m = {3.6072194965, -1.9405528295}

See similar equations:

| Log(100)=x | | 11x+4y=20 | | 5=7x+21 | | 5m^2+5m-21=0 | | 2e^3x+1=e^2 | | 45=y | | 3(3x+6)=8x+12 | | f(x)=2x^2+8x-20 | | 0.5=4.1x-2.6x-8 | | 50+5k=40 | | 8x+3=5-10x | | -4.9=5.1-2y | | 8x+3=5-10 | | 9c^3+12c^3+18c-9= | | 10x+12y=162 | | 3x^2+2xy+3y^2=4 | | (9x-1)=144 | | 2x^2+84x-5544=0 | | 37+13j=27j-5 | | -3(y+3)=5y-5+2(3y+4) | | 3a+13=10a-8 | | 2x^2+10=-1 | | 2/3w-1/4=(w-1/4) | | (3y-5y^3+4y^2-13)-(2y^2-9y^3+y-14)= | | -3y=5x-15 | | -216-(-60b)+8=32 | | -208+(-60b)=32 | | x*8+5=-1.2 | | 8+x=19-2 | | (X+13)(x)=(x+1)(x+10) | | X^2+y^2+2x-6y-6=0 | | 5[12-(6-3a)-2a]=(1-a) |

Equations solver categories