Question

what is If the sum of the square of the number and 4 times the number is 21,
what is the number?

Answer 1

Answer:

48 is the sum..........

Answer 2

Answer:

3

Step-by-step explanation:

x^2+4x=21

x^2+4x+4-4=21

(x+2)^2=21+4=25

(x+2)^2=5^2

x+2=5

x=5-2=3

So the number is 3

prove

(3)^2+4(3)=9+12=21