(x^2-7x-21)+(3x^2+5)=

Simple and best practice solution for (x^2-7x-21)+(3x^2+5)= 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 (x^2-7x-21)+(3x^2+5)= equation:


Simplifying
(x2 + -7x + -21) + (3x2 + 5) = 0

Reorder the terms:
(-21 + -7x + x2) + (3x2 + 5) = 0

Remove parenthesis around (-21 + -7x + x2)
-21 + -7x + x2 + (3x2 + 5) = 0

Reorder the terms:
-21 + -7x + x2 + (5 + 3x2) = 0

Remove parenthesis around (5 + 3x2)
-21 + -7x + x2 + 5 + 3x2 = 0

Reorder the terms:
-21 + 5 + -7x + x2 + 3x2 = 0

Combine like terms: -21 + 5 = -16
-16 + -7x + x2 + 3x2 = 0

Combine like terms: x2 + 3x2 = 4x2
-16 + -7x + 4x2 = 0

Solving
-16 + -7x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
-4 + -1.75x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + -1.75x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + -1.75x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1.75x + x2 = 0 + 4
-1.75x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
-1.75x + x2 = 4

The x term is -1.75x.  Take half its coefficient (-0.875).
Square it (0.765625) and add it to both sides.

Add '0.765625' to each side of the equation.
-1.75x + 0.765625 + x2 = 4 + 0.765625

Reorder the terms:
0.765625 + -1.75x + x2 = 4 + 0.765625

Combine like terms: 4 + 0.765625 = 4.765625
0.765625 + -1.75x + x2 = 4.765625

Factor a perfect square on the left side:
(x + -0.875)(x + -0.875) = 4.765625

Calculate the square root of the right side: 2.18303115

Break this problem into two subproblems by setting 
(x + -0.875) equal to 2.18303115 and -2.18303115.

Subproblem 1

x + -0.875 = 2.18303115 Simplifying x + -0.875 = 2.18303115 Reorder the terms: -0.875 + x = 2.18303115 Solving -0.875 + x = 2.18303115 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.875' to each side of the equation. -0.875 + 0.875 + x = 2.18303115 + 0.875 Combine like terms: -0.875 + 0.875 = 0.000 0.000 + x = 2.18303115 + 0.875 x = 2.18303115 + 0.875 Combine like terms: 2.18303115 + 0.875 = 3.05803115 x = 3.05803115 Simplifying x = 3.05803115

Subproblem 2

x + -0.875 = -2.18303115 Simplifying x + -0.875 = -2.18303115 Reorder the terms: -0.875 + x = -2.18303115 Solving -0.875 + x = -2.18303115 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.875' to each side of the equation. -0.875 + 0.875 + x = -2.18303115 + 0.875 Combine like terms: -0.875 + 0.875 = 0.000 0.000 + x = -2.18303115 + 0.875 x = -2.18303115 + 0.875 Combine like terms: -2.18303115 + 0.875 = -1.30803115 x = -1.30803115 Simplifying x = -1.30803115

Solution

The solution to the problem is based on the solutions from the subproblems. x = {3.05803115, -1.30803115}

See similar equations:

| 3x^2+x+0.25=3.25 | | 0.89x+24=1.49 | | 16=1-9y | | 3x=5-13 | | 9-2e(3-5e)= | | 3x-1(4x-3)=(3x+3)2x | | 8x+9x=204 | | 7x(X-13)=-35 | | 1/5×12= | | x/3-.5=5/6 | | V=40(1.03)(2/5x) | | 5(X-2)+3X=6-(4-2X) | | a^2+3a-50=0 | | 1/4x^2-1 | | 1/5×12 | | 2x(-8+3x)=3x(2x-4) | | f(x)=10x-3 | | 2(x+5)+8=10 | | 18x-(2x-3)=35 | | x^2+7x-58=0 | | sin(7x)-sin(6x)=0 | | a=-144/-11 | | 4n-28-12= | | m^2+7m-40=0 | | 3z+2=x+15 | | 4n-28= | | 13x+11=3x-169 | | y=3*0-6 | | 3x+14-2x=7+4x-5 | | 3x+15=x-13 | | -c/10-5=13 | | 4x+26y=9 |

Equations solver categories