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Solve the equation 1x2−8=0 / 2. The formula for nth term Progression is Rn-3. (i) Find one first term (ii) Find the common difference of 7 terms is 48.

Mathematics

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2 parts
i
-1

Step-by-step solution

4 steps

Here are the solutions to your problems.

: Solve the equation 1x2−8=01x^2 - 8 = 0

Step 1: Isolate the x2x^2 term.

x2−8=0x^2 - 8 = 0 x2=8x^2 = 8

Step 2: Take the square root of both sides. Remember to include both positive and negative roots.

x=±8x = \pm\sqrt{8} x=±4×2x = \pm\sqrt{4 \times 2} x=±22x = \pm 2\sqrt{2}

The solutions are x=22 or x=−22\boxed{x = 2\sqrt{2} \text{ or } x = -2\sqrt{2}}.

: Arithmetic Progression

The formula for the nthn^{th} term of an arithmetic progression is Tn=2n−3T_n = 2n-3.

Part i· 1 step

Find the first term

  1. To find the first term, substitute n=1n=1 into the formula for TnT_n.

    T1=2(1)−3T_1 = 2(1) - 3 T1=2−3T_1 = 2 - 3 T1=−1T_1 = -1

    The first term is −1\boxed{-1}.

Part ii5

Find the common difference if the sum of 5 terms is 45.

  1. We use the first term a=T1=−1a = T_1 = -1 found in part (i).

    We are given n=5n=5 and S5=45S_5 = 45.
    The formula for the sum of the first nn terms of an arithmetic progression is:

    Sn=n2(2a+(n−1)d)S_n = \frac{n}{2}(2a + (n-1)d)
  2. Substitute the known values into the sum formula.

    45=52(2(−1)+(5−1)d)45 = \frac{5}{2}(2(-1) + (5-1)d) 45=52(−2+4d)45 = \frac{5}{2}(-2 + 4d)
  3. Solve for dd.

    Multiply both sides by 2:

    45×2=5(−2+4d)45 \times 2 = 5(-2 + 4d) 90=5(−2+4d)90 = 5(-2 + 4d)

    Divide both sides by 5:

    905=−2+4d\frac{90}{5} = -2 + 4d 18=−2+4d18 = -2 + 4d

    Add 2 to both sides:

    18+2=4d18 + 2 = 4d 20=4d20 = 4d

    Divide by 4:

    d=204d = \frac{20}{4} d=5d = 5

    The common difference is 5\boxed{5}.

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