Power Play Class 8 Short Question Answer

Power Play Class 8 Short Question Answer

Power Play Class 8 Short Question Answer

Question 1.

If 5^3x-1 ÷ 25 = 125, then find the value of x.

Solution:

5^3x-1 ÷ 25 = 125 ⇒ 5^3x-1 ÷ 5² = 5³ ⇒ 5^3x-1-2= 5³

⇒ 5^3x-3 = 5³

⇒ 3x - 3 = 3 ⇒ 3x = 3 + 3 ⇒ 3x = 6

⇒ or x = [latex]\frac{6}{3}[/latex] = 2.

Question 2.

If p = 3 and q = 8, then find the value of (p³ × q^-2) × (p^-2 × q⁵ ).

Solution:

(p³ × q^-2) × (p^-2 × q⁵) = p^3-2 × q²⁺⁵ = pq³

So, value at p = 3 and g = 8 = 3 × 8³

= 3 × 512 = 1536.

Question 3.

Find the value of (3⁰ + 4^-1) × 2².

Solution:

(3⁰ + 4^-1) × 2²

= (1 + [latex]\frac{1}{4}[/latex]) × 4

= 4 + 4 × [latex]\frac{1}{4}[/latex]= 4 + 1 = 5.

Question 4.

Find the [latex]\left(\frac{5}{8}\right)^{-7}[/latex] × [latex]\left(\frac{8}{5}\right)^{-4}[/latex]

Solution:

[latex]\left(\frac{5}{8}\right)^{-7}[/latex] × [latex]\left(\frac{8}{5}\right)^{-4}[/latex] = [latex]\left(\frac{8}{5}\right)^7[/latex] × [latex]\left(\frac{8}{5}\right)^{-4}[/latex]

= [latex]\left(\frac{8}{5}\right)^{7-4}[/latex] = [latex]\left(\frac{8}{5}\right)^3[/latex]

= [latex]\frac{8^3}{5^3}[/latex] = [latex]\frac{512}{125}[/latex]

Question 5.

Write 0.000000564 in the scientific notation.

Solution:

0.000000564 = [latex]\frac{564}{1000000000}[/latex] = [latex]\frac{564}{10^9}[/latex]

= 564 × 10^-9

= 564 × [latex]\frac{10^{-7}}{10^2}[/latex]

= 5.64 × 10^-7