Using long division, divide 2x3−7x2+2x+32x^{3}-7x^{2}+2x+3 by 2x−42x-4. Solve 2x3−7x2+2x+3=02x^{3}-7x^{2}+2x+3=0. Kun Ye claims that the solutions to the equation 2x3−7x2+2x+3=02x^{3}-7x^{2}+2x+3=0 can be used to solve 3y6+2y4−7y2+2=03y^{6}+2y^{4}-7y^{2}+2=0. Explain how he is correct.

Work through it with AI →

It won't just hand you the answer — it asks where you're stuck.How the checker works

Worked solution

8(a)

1. Set up the long division and find the first term of the quotient.

Divide the leading term 2x32x^3 by 2x2x to get x2x^2.
Multiply x2x^2 by (2x−4)(2x-4) to get 2x3−4x22x^3 - 4x^2.
Subtract this from 2x3−7x22x^3 - 7x^2 to get −3x2-3x^2, and bring down the next term 2x2x.

2. Find the second term of the quotient.

Divide −3x2-3x^2 by 2x2x to get −32x-\frac{3}{2}x.
Multiply −32x-\frac{3}{2}x by (2x−4)(2x-4) to get −3x2+6x-3x^2 + 6x.
Subtract this from −3x2+2x-3x^2 + 2x to get −4x-4x, and bring down the 33.

3. Find the final term of the quotient and the remainder.

Divide −4x-4x by 2x2x to get −2-2.
Multiply −2-2 by (2x−4)(2x-4) to get −4x+8-4x + 8.
Subtract this from −4x+3-4x + 3 to get a remainder of −5-5.

Answer

Quotient: x2−32x−2x^2 - \frac{3}{2}x - 2, Remainder: −5-5

8(b)

1. Use the Factor Theorem to find a linear factor of the polynomial.

Let f(x)=2x3−7x2+2x+3f(x) = 2x^{3} - 7x^{2} + 2x + 3.
f(1)=2(1)3−7(1)2+2(1)+3=2−7+2+3=0f(1) = 2(1)^{3} - 7(1)^{2} + 2(1) + 3 = 2 - 7 + 2 + 3 = 0
Since f(1)=0f(1) = 0, (x−1)(x - 1) is a factor.

2. Find the quadratic factor by dividing the cubic polynomial by the linear factor.

2x3−7x2+2x+3=(x−1)(ax2+bx+c)2x^{3} - 7x^{2} + 2x + 3 = (x - 1)(ax^{2} + bx + c)
By inspection or long division:
a=2a = 2 and c=−3c = -3.
Comparing coefficients of x2x^{2}:
−a+b=−7  ⟹  −2+b=−7  ⟹  b=−5-a + b = -7 \implies -2 + b = -7 \implies b = -5
So, the quadratic factor is 2x2−5x−32x^{2} - 5x - 3.

3. Factorise the quadratic factor completely.

2x2−5x−3=(2x+1)(x−3)2x^{2} - 5x - 3 = (2x + 1)(x - 3)

4. Solve the equation to find all values of $x$.

(x−1)(2x+1)(x−3)=0(x - 1)(2x + 1)(x - 3) = 0
x−1=0  ⟹  x=1x - 1 = 0 \implies x = 1
2x+1=0  ⟹  x=−122x + 1 = 0 \implies x = -\frac{1}{2}
x−3=0  ⟹  x=3x - 3 = 0 \implies x = 3

Answer

x=−12,x=1,x=3x = -\frac{1}{2}, x = 1, x = 3

8(c)

1. Identify the relationship between the two equations by substituting $x = \frac{1}{y^2}$

Let x=1y2x = \frac{1}{y^2}.
Substitute into 2x3−7x2+2x+3=02x^3 - 7x^2 + 2x + 3 = 0:
2(1y2)3−7(1y2)2+2(1y2)+3=02\left(\frac{1}{y^2}\right)^3 - 7\left(\frac{1}{y^2}\right)^2 + 2\left(\frac{1}{y^2}\right) + 3 = 0
2y6−7y4+2y2+3=0\frac{2}{y^6} - \frac{7}{y^4} + \frac{2}{y^2} + 3 = 0

2. Multiply by $y^6$ to obtain the second equation

Multiply the entire equation by y6y^6:
2−7y2+2y4+3y6=02 - 7y^2 + 2y^4 + 3y^6 = 0
Rearranging the terms gives:
3y6+2y4−7y2+2=03y^6 + 2y^4 - 7y^2 + 2 = 0
This matches the second equation, showing that if xx is a solution to the first equation, then yy where y2=1xy^2 = \frac{1}{x} is a solution to the second.

Answer

By substituting x=1y2x = \frac{1}{y^2} into 2x3−7x2+2x+3=02x^3 - 7x^2 + 2x + 3 = 0 and multiplying by y6y^6, we obtain 3y6+2y4−7y2+2=03y^6 + 2y^4 - 7y^2 + 2 = 0. Thus, the solutions for xx can be used to find yy.

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1Express 2x4+x3+9x2+7x+3(x+1)(x2+5)\frac{2x^4 + x^3 + 9x^2 + 7x + 3}{(x+1)(x^2+5)} in partial fractions.
  2. 2It is given that 2x×32(2x)8x+1=9(52x)−52x+15x−5x−1\frac{2^x \times 32(2^x)}{8^{x+1}} = \frac{9(5^{2x}) - 5^{2x+1}}{5^x - 5^{x-1}}. Evaluate 10x10^x with…
  3. 3Express 2x2+3xx2+3x+2\dfrac{2x^{2}+3x}{x^{2}+3x+2} in partial fractions. Hence evaluate ∫132x2+3xx2+3x+2 dx\displaystyle \int_{1}^{3} \dfrac{2x^{2}+3x}{x^{2}+3x+2}\,dx…
  4. 4Find, in ascending powers of xx, the first three terms in the expansion of (1+4x)7(1+4x)^7, (2−x)7(2-x)^7. Hence, find the coeff…
  5. 5The diagram shows part of the curve y=(1−x)(x−4)y = (1 - x)(x - 4) and two lines l1l_1 and l2l_2. The lines l1l_1 and l2l_2 are ta…