Answer:
Option A is correct, i.e. x = -3, x = 7.
Step-by-step explanation:
Given the equation is x² -4x -21 = 0.
We can compare it with general quadratic equation i.e. ax² +bx +c =0.
then a = 1, b = -4, c = -21.
We can use Quadratic formula as follows:-
x = ( -b ± √(b²-4ac) )/2a
x = ( +4 ± √(16-4*1*-21) )/2*1
x = ( +4 ± √(16+84) )/2
x = ( +4 ± √(100) )/2
x = ( +4 ± 10 )/2
x = (4+10)/2 or x = (4-10)/2
x = 14/2 or x = -6/2
x = 7 or x = -3
Hence, option A is correct, i.e. x = -3, x = 7.
Answer:
largeness
Step-by-step explanation:
look up in dictionary
Answer:
The Answer us 65 but why don't you get some answer choices little buddy
Answer:
What do you need help with? :P
Step-by-step explanation:
Hav a gud day :3
Answer:
Width= 85
Length= 485
Step-by-step explanation:
The width will be x, and the length will be x + 400, since it is 400 more than the width.
We know that the perimeter of a rectangle can be found using the equation 2w + 2l.
We plug in the values we have found.
2(x) + 2(x+400) = 1140
4x + 800 = 1140
4x = 340
x = 85
Now we know the width, since it is simply x. To find length all we have to do is add 400.
400 + 85 = 485
