Question 71
If $$2x + 3y + 1 = 0$$, then what is the value of $$\left(8x^3 + 8 + 27y^3 - 18xy \right)$$?
Solution
$$2x+3y+1=0$$
$$2x+3y=-1$$........(1)
Cubing on both sides,
$$8x^3+27y^3+3.2x.3y\left(2x+3y\right)=-1$$
$$8x^3+27y^3+18xy\left(-1\right)=-1$$
$$8x^3+27y^3-18xy+8=-1+8$$
$$8x^3+27y^3-18xy+8=7$$
Hence, the correct answer is Option B
Get AI Help
Create a FREE account and get:
- Free SSC Study Material - 18000 Questions
- 230+ SSC previous papers with solutions PDF
- 100+ SSC Online Tests for Free
