If Y is directly proportional to X² and y=21 when x=2, find the value of y when X=4.

Step-by-step explanation:

it means y/x^2=k

when y=21, x=2; k is 21/4.

when x=4, k is y/16.

k=21/4=y/16.

the next step is easy to see, you can do it.

the correct answer option is (2x-3)(2x+3).

step-by-step explanation:

we are given the following expression and we are to factorize it:

we are to find such factors that when multiplied they give a result of 36 (9 x 4 = 36) and when added they give a result of 0.

the two such factors of 36 are negative six and postive six.

factorizing the given expression to get:

therefore, the correct factorization of is (2x-3)(2x+3).

the awnser is visionary