Question

if square of number is added to 3times the number the sum is 28 find number​

Answer 1

Answer:

If we word this into an equation, we get x² + 3x = 28

This is a form of quadratic equations, where we move the 28 from the right hand side to the left hand side.

Making x² + 3x - 28 = 0

It's now in the form we know as ax² + bx +c = 0

The 28 is in negative as it was positive on the right side and now it's negative.

If we use the quadratic formula, which is -b ± √(b² - 4ac) then divide the whole thing by 2a.

After substituting the values in (a = 1, b = 3, c = -28)

We get -3 ± √(3² - 4(1)(-28)) ÷ 2(1)

Which then simplifies to -3 ± (√121) ÷ 2

Which gives -3 ± 11 then divided by 2

So you should get 2 answers, -3 + 11 which is 8, then divided by 2 is 4

Second answer should be -3 - 11, which is - 14, then divided 2 is -7.

So x = -7 or x = 4

Step-by-step explanation: