0
x2-4x -21 = 0
(x-7)(x+3) = 0
x = -3 or x = 7
Alternate
x2 - 4x - 21 = 0
x = (-b ± (b2 - 4ac )(1/2)) ÷ 2a
x = (+4 ± (42 - 4*1*(-21))(1/2)) ÷ 2*1
x = (+4 ± (100)(1/2)) ÷ 2
x = (+4 ± 10) ÷ 2
x = (+2 ± 5)
x = -3 ^ x = +7
What else can I help you with?
What is a if the square root of 4a squared equals 21?
sqrt(4a2) = 21plus or minus (2a) = 21plus or minus (a) = 10.5a = +10.5a = -10.5
How do you solve 3x minus 6 equals 21?
3x-6 = 21 3x = 21+6 x = (21+6)/3 x = 9 You shouldn't ask us to solve your math homework.
How do you solve 4n minus 7n equals 21?
4n - 7n = 21(4-7) n =21-3n = 21divide both sides by -3n = -7
How do you factor x squared minus 4x minus 21?
x2 - 4x - 21 = (x-7)(x+3)
What is the answer to 16 over 21 minus 2?
16/21 minus two equals -1 5/21
What is a if the square root of 4a squared equals 21?
sqrt(4a2) = 21plus or minus (2a) = 21plus or minus (a) = 10.5a = +10.5a = -10.5
Solve 21 equals 13 minus 2b?
This is the same as: 13-2b = 21 -2b = 21-13 -2b = 8 b = -4
How do you solve 3x minus 6 equals 21?
3x-6 = 21 3x = 21+6 x = (21+6)/3 x = 9 You shouldn't ask us to solve your math homework.
How do you solve 4n minus 7n equals 21?
4n - 7n = 21(4-7) n =21-3n = 21divide both sides by -3n = -7
How do you factor x squared minus 4x minus 21?
x2 - 4x - 21 = (x-7)(x+3)
What is the answer to 16 over 21 minus 2?
16/21 minus two equals -1 5/21
What equals 21 minus 12?
9
How do you solve for the problem x squared minus 10 equals 4x plus 11?
x2-10 = 4x+11 x2-4x-10-11 = 0 x2-4x-21 = 0 (x+3)(x-7) = 0 x = -3 and x = 7
How do you solve 2 x minus 5 equals 16?
you add the 5 to both sides of the equation and you have 2x=21 and then you divide by 2 so you have x=11
Solve a plus 9 equals 21?
A + 9 = 21 A = 21 - 9 A = 12
How do you solve 4x squared minus 21 equals negative 11x?
The Quadratic Formula gives the value of x in equations of the form ax2 + bx + c. In this instance a = 4, b = 11 and c = -21. ((-b +/-(sqrt(b2 - 4ac))/2a = (-11 +/- sqrt (121 + 336))/ 8 = (-11 +/- 21.4)/8 x = 1.3 or 4.05
What is minus 12 minus 9?
minus 21 think of it as 12+9 which equals 21 then just whack a minus sign infront
