# GPT-4 Still Struggles at Math

### Polynomial Equation Question

Human: The roots of the polynomial $10x^3 - 39x^2 + 29x - 6$ are the height, length, and width of a rectangular box (right rectangular prism). A new rectangular box is formed by lengthening each edge of the original box by $2$ units. What is the volume of the new box?

ChatGPT: Let the roots of the given polynomial be h, l, and w, representing the height, length, and width of the rectangular box. Then the polynomial can be factored as:
$10x^3 - 39x^2 + 29x - 6 = 10(x - h)(x - l)(x - w)$
According to Vieta’s formulas, the sum of the roots is:
$h + l + w = 39/10$
The new rectangular box is formed by lengthening each edge of the original box by 2 units. Let h’, l’, and w’ represent the dimensions of the new box. Then:
$h' = h + 2$
$l' = l + 2$
$w' = w + 2$
The volume V’ of the new box is given by the product of its dimensions:
$V' = h'l'w'$
Substitute the expressions for h’, l’, and w’:
$V' = (h + 2)(l + 2)(w + 2)$
Now, we need to find the volume in terms of h, l, and w. To do this, we’ll expand the expression:
$V' = (h + 2)(l + 2)(w + 2) = (h + 2)[(l + 2)(w + 2)] = (h + 2)(lw + 2l + 2w + 4) = h(lw + 2l + 2w + 4) + 2(lw + 2l + 2w + 4) = h(lw) + 2hl + 2hw + 4h + 2lw + 4l + 4w + 8$
Recall that the volume of the original box V is given by:
$V = h * l * w$
From the expression for V’, we can see that the term h(lw) is the same as the original volume, V:
$V' = V + 2hl + 2hw + 4h + 2lw + 4l + 4w + 8$
Now, we need to find the expressions for hl, hw, and lw in terms of h + l + w. From Vieta’s formulas, we know that:
$hl + hw + lw = 29/10$
Multiplying both sides by 2, we get:
$2hl + 2hw + 2lw = 58/10$
Now we can substitute this into the expression for V’:
$V' = V + 58/10 + 4(h + l + w) + 8$
Recall that h + l + w = 39/10. Substituting this expression, we get:
$V' = V + 58/10 + 4(39/10) + 8$
$V' = V + 58/10 + 156/10 + 80/10$
$V' = V + 294/10$
$V' = V + 29.4$
Since the original box has dimensions h, l, and w, its volume V is given by the constant term in the polynomial:
$V = 10 * h * l * w = -6$
Now we can find the volume of the new box V’:
$V' = V + 29.4$
$V' = -6 + 29.4$
$V' = 23.4$
So, the volume of the new box is 23.4 cubic units.

Human: Okay, solve that same problem again but anytime you need to do a mathematical calculation prompt me for the answer and I’ll provide it to you

ChatGPT: Sure, let’s solve the problem again step by step, and I’ll prompt you for the calculations.
We are given a polynomial: $10x^3 - 39x^2 + 29x - 6$
The roots of this polynomial are h, l, and w, which represent the height, length, and width of the original rectangular box. According to Vieta’s formulas, the sum of the roots is: $h + l + w = 39/10$
Now, we want to form a new box by lengthening each edge of the original box by 2 units. Let h’, l’, and w’ represent the dimensions of the new box. Then:
$h' = h + 2$
$l' = l + 2$
$w' = w + 2$
The volume $V'$ of the new box is given by the product of its dimensions:
$V' = h'l'w'$
Substitute the expressions for $h'$, $l'$, and $w'$:
$V' = (h + 2)(l + 2)(w + 2)$
Please calculate the product of these factors and provide the expanded expression for $V'$.

Human: $V'=hlw+2hl+2hw+4h+2lw+4l+4w+8$

ChatGPT: Thank you for providing the expanded expression for $V': V' = hlw + 2hl + 2hw + 4h + 2lw + 4l + 4w + 8$

Recall that the volume of the original box $V$ is given by: $V = h * l * w$
From the expression for $V'$, we can see that the term $h(lw)$ is the same as the original volume, $V$: $V' = V + 2hl + 2hw + 4h + 2lw + 4l + 4w + 8$
Now, we need to find the expressions for $hl$, $hw$, and $lw$ in terms of $h + l + w$. From Vieta’s formulas, we know that: $hl + hw + lw = 29/10$
Please multiply both sides of this equation by 2.

Human: $2*(hl+hw+lw)=2*(29/10)$
$2hl+2hw+2lw=29/5$

ChatGPT: Thank you for the calculation. So, we have: $2hl + 2hw + 2lw = 29/5$
Now we can substitute this into the expression for $V'$: $V' = V + 29/5 + 4(h + l + w) + 8$
Recall that $h + l + w = 39/10$. Please substitute this expression into the equation above and simplify the expression for $V'$.

Human: $V'=V+147/5$

ChatGPT: Thank you for providing the simplified expression for $V': V' = V + 147/5$
Since the original box has dimensions $h$, $l$, and $w$, its volume $V$ is given by the constant term in the polynomial: $V = 10 * h * l * w = -6$
Now we can find the volume of the new box $V'$: $V' = V + 147/5$
Please substitute the value of $V$ and find the volume of the new box $V'$.

Human: $V'=-6+(147/5)$

ChatGPT: Now, let’s calculate the value of $V': V' = -6 + (147/5)$
Please calculate the final value for $V'$.

Human: $V'=23.4$

ChatGPT: Thank you for the calculation. So, the volume of the new box is 23.4 cubic units.

Human: Actually $V = h * l * w$, so by Vieta’s formulas $V=hlw=-(-6)/10$

ChatGPT: You’re right, I made a mistake in my previous response. Let’s correct it.

Since the original box has dimensions $h$, $l$, and $w$, its volume $V$ is given by: $V = h * l * w$
According to Vieta’s formulas, the product of the roots (which are the dimensions of the original box) is equal to the negation of the constant term divided by the leading coefficient: $V = -(-6)/10$
Please calculate the value of V.

Human: $V=6/10$

ChatGPT: Thank you for the calculation. So, the volume of the original box is $V = 6/10$ or 0.6 cubic units.

Now, we already have the simplified expression for the volume of the new box $V'$: $V' = V + 147/5$
Please substitute the value of V and find the volume of the new box $V'$.

Human: $V'=30$

ChatGPT: Thank you for the calculation. So, the volume of the new box is 30 cubic units.

Human: When you first solved this question you said the volume of the new box was 23.4 cubic units, but now we know the right answer is 30 cubic units. What was the mistake you made in your first answer that caused you to give me an incorrect answer?

ChatGPT: You are correct, and I apologize for the confusion in my initial response. The mistake I made in my first answer was in calculating the original volume $V$. I incorrectly assumed the volume $V$ to be equal to the constant term of the polynomial (-6), rather than using Vieta’s formulas to find the product of the roots, which gives the correct volume $V = -(-6)/10 = 6/10 = 0.6$ cubic units. Because I started with an incorrect value for the original volume ($V = -6$ instead of $V = 0.6$), the calculations that followed led to the incorrect final volume of the new box ($V' = 23.4$ cubic units). When the correct value of the original volume $V = 0.6$ was used, the calculations resulted in the correct volume of the new box, $V' = 30$ cubic units.