Factor the expression completely.
-x^4-4x^2+21

-(x^2-3)(x^2+7) Is the answer

Step-by-step explanation:

The first term is,  x4  its coefficient is  1 .

The middle term is,  +4x2  its coefficient is  4 .

The last term, "the constant", is  -21

Step-1 : Multiply the coefficient of the first term by the constant   1 • -21 = -21

Step-2 : Find two factors of  -21  whose sum equals the coefficient of the middle term, which is   4 .

     -21    +    1    =    -20

     -7    +    3    =    -4

     -3    +    7    =    4    That's it

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -3  and  7

                    x4 - 3x2 + 7x2 - 21

Step-4 : Add up the first 2 terms, pulling out like factors :

                   x2 • (x2-3)

             Add up the last 2 terms, pulling out common factors :

                   7 • (x2-3)

Step-5 : Add up the four terms of step 4 :

                   -(x^2-3)(x^2+7)

            Which is the desired factorization

(Hope this helps can I pls have brainlist (crown) ☺️)

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

363 square inches

step-by-step explanation:

surface area of a pyramid is b + 1/2ph

b is the area of the base: 11 x 11 = 121

p is the perimeter of the base: 11 + 11 + 11 + 11 = 44

h is the height of the pyramid: 11

121 + 1/2(44)(11)

121 + 242

363