Question

He steps to derive the quadratic formula are shown below:

Step 1 ax2 + bx + c = 0
Step 2 ax2 + bx = - c
Step 3 x2 + b over a times x equals negative c over a
Step 4x2 + b over a times x plus b squared over 4 times a squared equals negative c over a
Step 5 x2 + b over a times x plus b squared over 4 times a squared equals negative 4 multiplied by a multiplied by c, all over 4 multiplied by a squared plus b squared over 4 times a squared
Step 6 the square of the quantity x plus b over 2 times a equals b squared minus 4 multiplied by a multiplied by c, all over 4 times a squared
Step 7 x plus b over 2 times a equals plus or minus square root of the quantity b squared minus 4 times a times c over 4 times a squared equals plus or minus square root of b squared minus 4 times a times c, all divided by 2 times a
Step 8 x = -negative b over 2 times a plus or minus square root of b squared minus 4 times a times c, all divided by 2 times a
Step 9 x = negative b plus or minus square root of b squared minus 4 times a times c, all divided by 2 times a Which of the following is the first incorrect step?
A. Step 4

B. Step 6

C. Step 7

D. Step 8

Answer 1

step 4 is wrong hope this helps

Answer 2

imma translate all the steps into numbers so it's easier to see and the reason we got to that step

1.
`ax^2+bx+c=0`
given

2.
`ax^2+bx=-c`
minus c from both sides

3.
`x^2+(b)/(a)=(-c)/(a)`
divide both sides by a

4.
`x^2+(bx)/(a)+(b^2)/(4a^2)=(-c)/(a)`
add
`(b^2)/(4a^2)` to both sides, wait, we didn't add it to both sides, only the left side, MISTAKE!

so step 4 is wrong step