Solve the quadratic equation by square roots: 1. 4x²= 81 2. (4x-3)²+7=39

Mathematics

1 answer:

Nataly [62]3 years ago

7 0

Answer:

see explanation

Step-by-step explanation:

(1)

given

4x² = 81 ( divide both sides by 4 )

x² = $\frac{81}{4}$ ( take the square root of both sides )

x = ± $\sqrt{\frac{81}{4} }$ = ± $\frac{9}{2}$

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(2)

subtract 7 from both sides

(4x - 3)² = 32 ( take the square root of both sides )

4x - 3 = ± $\sqrt{32}$ = ± 4 $\sqrt{2}$

Add 3 to both sides

4x = 3 ± 4 $\sqrt{2}$ ( divide both sides by 4 )

x = $\frac{3}{4}$ ± $\sqrt{2}$

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