What is the number that represents x in 12x + 5 = 8x + 21?

I hope this helps you

12x-8x=21-5

4x=16

x=4

X is equal to 4 because:
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Step 1: 12*4+5
Step 2: 48+5=53
This is the answer for the first equation, next, you find the answer to the next equation.
Step 3: 8*4+21
Step 4: 32+21=53
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53 is equal to 53, therefore x=4.

The surface area would be 576 because you multiply all the numbers then multiply that number by 6

Answer to your question: a. the fundamental theorem of algebra tells you that the equation will have two complex roots since the degree of the polynomial is 2. the roots are ​ x=1±i7√2 .number of roots=degree of polynomialhere, degree of polynomial is 2 so number of roots will be 2.hope it *_*