Question

Two of the steps in the derivation of the quadratic formula are shown below. Step 6: StartFraction b squared minus 4 a c Over 4 a squared EndFraction = (x + StartFraction b Over 2 a EndFraction) squared Step 7: StartFraction plus or minus StartRoot b squared minus 4 a c EndRoot Over 1 a EndFraction = x + StartFraction b Over 2 a EndFraction Which operation is performed in the derivation of the quadratic formula moving from Step 6 to Step 7? subtracting StartFraction b Over 2 a EndFraction from both sides of the equation squaring both sides of the equation taking the square root of both sides of the equation taking the square root of the discriminant

Answer 1

Explanation:

From the step given step 6

(b² — 4ac) / 4a² = (x + b/2a)²

Mistake in question it is (x + b/2a)²

Step 7 given

±√(b² —4ac) /2a = x + b/2a

Mistake in question it is over 2a and not 1a.

1. The step taken from step 6 to step 7 is taking square roots of both sides

(b² — 4ac) / 4a² = (x + b/2a)²

Taking square of both sodes

√(b²—4ac) / √4a² = √(x + b/2a)²

√(b²—4ac) / 2a = x + b/2a

This is the required step 7.

Now, subtracting b/2a from both sides

√(b²—4ac) / 2a - b/2a= x + b/2a -b/2a

√(b²—4ac) / 2a — b/2a = x

(√(b²—4ac) — b)/2a = x

x = [—b ± √(b²—4ac)] / 2a

So, this is the required formula method

The discriminant is D = b²—4ac.

Answer 2

c

Explanation:

taking the square root of both sides of the equation