Question

I’d really appreciate help with these...

Answer 1

Answer:

+- 5 and +- 3

Step-by-step explanation:

qn 2:

4r² = 91 + 9

4r² = 100

r² = 25

r = +- 5

qn 3:

4r² = 29 + 7

4r² = 36

r² = 9

r = +- 3

Answer 2

Answer:

Q2. (±5)

Q3. (±3)

Step-by-step explanation:

$\bold{Q2.}\\\\4r^2-9=91\qquad\text{add 9 to both sides}\\\\4r^2-9+9=91+9\\\\4r^2=100\qquad\text{divide both sides by 4}\\\\\dfrac{4r^2}{4}=\dfrac{100}{4}\\\\r^2=25\to r=\pm\sqrt{25}\\\\\boxed{r=\pm5}$

$\bold{Q3.}\\\\4r^2-7=29\qquad\text{add 7 to both sides}\\\\4r^2-7+7=29+7\\\\4r^2=36\qquad\text{divide both sides by 4}\\\\\dfrac{4r^2}{4}=\dfrac{36}{4}\\\\r^2=9\to r=\pm\sqrt9\\\\\boxed{r=\pm3}$